With all the talk around about 4G and the wireless industry, before we can get into what is 4G and LTE Technology, let’s take a little trip down memory lane with the Mobile phone. We need to take a quick look at the evolution over the years that this technology has made.
This was known as the first generation of wireless. It was first introduced to the world in the 80’s and used an analog technology. It was where phones such as the brick phone or car phones would put out 3 watts of power for better range and a cellular tower could cover an area of about 40 to 50 miles without any issues due to the lack of data transmissions and the error correcting it requires, it was strictly used for voice phone calls. The phones were larger in size and a lot more durable.
Next came the second generation of wireless technology. This evolved came about in the early 90’s and was the introduction of digital such as TDMA, CDMA 1X and GSM GPRS came into the picture. This was when data on the phone began its existence. It was still very slow data but it was a beginning and the consumer started to have the options of surfing the internet while on the move. The phones got a lot smaller and due to the digital technology and the error corrections needed for data, coverage started to degrease on sites requiring carriers to deploy more sites for a particular area. It also is when the power on the phones started to degrease to allow for more battery life due to the sites were closer together and the signal not needing to travel as far.
***Note*** All Generations after this point were just developed to increase the speeds of data for the consumer and to allow them a better internet experience while on the move.
This generation was a bridge between 2G and 3G. It was basically a change made to the GSM technology moving it from GPRS to EDGE. This change increased the data speeds for customers.
Third Generation of Wireless was a major breakthrough with data speeds. With this generation speeds on devices move to as high as 3.1MB per second. It was when the development of CDMA EVDO was first introduced.
This generation was once again just a Bridge between 3G and 4G. it was the deployment of UMTS and HSPA+. Some wireless carriers advertise that HSPA+ is 4G but the ITU does not recognize this and considers it 3.5G.
Now let’s talk about the fourth generation of wireless technology. ITU states 4G is anything up to 100Mb per second. However they do state that they consider LTE to be 4G even though it doesn’t meet this requirement. LTE stands for Long Term Evolution and was a major breakthrough in data speeds. We are now seeing speeds up to approximately 22Mb per second or more. However, to support these speeds many things had to change as far as infrastructure for the carrier. You know have to have more band width to a cell site than ever imagined needing. This puts a big burden on carriers to support. If you think about it. If you have let’s say 10 customers on a site all wanting to do 22Mb per second, the carrier has to have 220MB of bandwidth just to that one site.
Due to this increase in bandwidth at both the cell site and at the switching locations, there has been a very limited deployment, to date, of this technology. The deployment will increase but as you can imagine it starts in the major cities and moves out as customer demand increases. Smaller communities may not see LTE deployed in their area for some time.
I must also mention there is one other form of 4G wireless technology that ITU recognizes and that is WiMax. WiMax has far superior data speeds for the consumer but there are major drawbacks for carriers such as the foot print the cell site covers from one location. They are very limited in coverage and thus require many more sites. Also very few of the major Wireless Carriers have opt to use this technology so roaming options are very limited.
There are two issues with 4G/LTE technology that the consumers should be aware of:
1) As wireless carriers are not held to any standard as far as advertising. Some carriers are actually still 3G or 3.5G with speeds but still advertise they are 4G. Some actually considered 3.5G to be 4G and thus confuse the consumer with their advertising. I have even seen carriers stating they are 4G but still sell the same phones and devices as when they were 3G.
2) Since all wireless carriers will now be using the same technology. It benefits the consumer by letting a phone work with different carriers but it also means that the smaller carriers that survive on roaming revenue can see that loss of revenue due to less roaming partners a carrier needs. That may force some of the smaller carriers out of business and that in itself is not good for consumers when it comes to competition.
In closing, as 4G and LTE still new to the consumer and the wireless industry, a lot of issues that may evolve have not all yet been discovered. Let’s just hope that this technology actually turns out to be as great as all the hype is over it in the world. Also let’s hope that since the speeds are so great and the costs to support those speeds are great to the carrier, that we don’t see data plan costs go up. We already see a lot of the carriers starting to implement limits and either charging you for going over or slowing you back down to 2G speeds when you reach your limit.
If a wireless phone tower only covers a few square miles, how is it, I can travel for miles and never drop my call with the person I am talking to?
The first thing I will need to explain to you are some basic wireless terms that will be used in this article.
1) BTS: Stands for Base Station Controller. It is a fancy name for a cell site
2) BSC: Base Station Controller. Controls all messaging back and forth to the BTS
3) MSC: Mobile Station Controller. This is the main switching computer that controls the BSC and all call traffic
4) CDMA/GSM or UMTS: These are different Digital Technologies used by wireless carriers
Now let’s start talking a little about how this all works.
First you will need to set up a call on your wireless phone. Once you are on that particular call you begin driving down the road. There is a slight difference in this process between GSM and CDMA. I will attempt to point them out as we go through this. As you are on the phone, your signal is constantly being monitored and evaluated, also each BTS on the BSC has a database that lists all the corresponding sites around it that a customer could possibly drive into the area of.
The next step there is a difference in how it works:
CDMA / UMTS: In CDMA and UMTS, your call is actually being processed but all the surrounding sites at the same time. The BSC monitors the signal quality on the call and as you drive, the levels will get better on one site over another and the BSC just process the call on the best quality site. As you drive on, your noise level changes, and the BSC will just process the call from the new site. This is called Soft Hand Off’s. As you drive on, this process is just repeated over and over with the sites going down the road based on the BSC database listing of the surrounding sites.
GSM: In GSM it works a little different. The calls are not actually processed over multiple sites at one time, because the phone in GSM is forced to retune to a different Freq every time you move from one site to another. So how it works, is it just monitors your signal level on all surrounding sites based on the BSC database. Then once your signal level is stronger on one of the neighbor sites than the one you currently are on, the phone receives a message from the BSC telling it to retune to the channel of the neighbor site and the phone retunes and the call hands off.
Because of these differences, if you listen closely, you may hear a small click or a word of audio may be muted because of the retuning of the phone. In CDMA, all sites actually operate on the same frequency and it performs a Soft Hand Off, so it is seamless to the customer and device.
The signal levels that these processes us to compare and performed at are also set by the carrier in their BSC database.
The number one reason for a consumer to drop their call is usually a neighbor cell site is not loaded properly in the BSC as a hand off candidate or that possibly the signal levels that are set in the database may need to be adjusted slightly. This process is not an exact art for all situations so drop calls will happen that cannot be explained.
Now let me explain quickly how this whole process works when you drive on a road where one area is on one wireless carrier system and the other area is on someone else’s wireless system. Because this requires two different carriers to be involved, many times your calls will just drop because the two carriers have not gone into an agreement among themselves, most of the times this is due to costs associated in putting the process in place.
If both carriers decide they want to put this in place, it is very similar to what already happens above. The difference is, that the BSC database also has to have information on the neighbor BTS’s. However, when it needs to get info of the neighbor’s site it has to communicate over a link that is put in place connecting the two companies. If the call actually reaches levels that it hands off the call, the neighbor has to take the audio for that call also and that requires some sophisticated signaling and trunking to be in place. Also due to the time it takes for all this messaging to take place between carriers, it is not uncommon for the calls to drop if the areas terrain is hilly or the customer drives too quickly through. The costs associated with this, is the main reason carriers do not put this in place. You will usually only see this in place if the area in question is on a major interstate or where there is enough traffic to justify not dropping the calls.
I hope this all made sense to you and if not feel free to drop me a note or comment and I will try to answer your questions for you.
I will try below to explain to people how a Mobile phone call takes place.
First you have to realize that on every mobile phone system their is a computer system called a HLR (Home Location Register). These computers have everything about your phone programmed into it. Such as your Phone Number, Serial Number, what types of calls you are allowed to make and which ones you are not, and what features you have purchased from the carrier.
Now let’s see what happens when you first power up the phone. The phone will first start to receive signals from all the cell sites in the area. This is all cell sites and not just the ones from your carrier you have service with. Inside your phone is a database that stores all the information on the different carriers and systems it is allowed to make calls on. It also lists all this data in a priority level as to which ones to look for first. The phone will then look by priority to see which systems it can see and lock on to.
Once the mobile phone locks onto a particular system it will transmit to the cell site its mobile number and its serial number. This information will be passed on to the switch and then on to the HLR for verification. If you are roaming there is a computer called VLR (Visitor Location Register) that will get the info from the HLR and store it for future use.
If this verification take place it will then light the in-service light on the phone and allow you to make calls. Now let’s see what happens when everything is validated and you dial a number on your phone and hit SEND.
Lets first understand some of the systems at a cell site and switch. These are the systems that will be used to translate the call. Once you understand those then everything else falls into place quickly. First, in the RF signal, in the air to your phone, is two types of signals. One is called a control signal or overhead channel and the other one is called a voice channel. The control signal is where all the data is transmitted on. This is the info such as your phone number, serial number, and the digits you have dialed. The voice cannel is where the call will be placed once it is processed and ringing starts and you need to get two way audio for the call. The transmitters at the cell site communicate with the switch via a cable or fiber provided by the phone company back to another system called the switch. This switch is where everything is actually controlled from and will be explained more later on. Then from there you have more phone lines to the land line phone company for getting the call to someone’s house. Now let’s talk about your particular call.
Let’s say you dial your house and its number is 555-234-1122. First, the phone will send the info to the cell site on the control overhead channel. The cell sites transmitter will take this info and send it on to the switch to be processed. This message is sent via the fiber cable it has connecting the cell site to the switch. You can have one switch running hundreds of cell sites. The switch will then do a few things before allowing the call. First it will check with your HLR/VLR entry and see if you are allowed that type of call. If it is a valid call, it will then check another database to see what to do with the digits you dialed. It also has to verify the digits are a valid number of digits for a phone call. With this check it will also be looking up where this number is located and who it should forward the call to, either a local telephone company or a long distance carrier. Once this is completed, it will forward on the digits to the land line phone company. Once they get it they deliver it to the appropriate place. Once the call is sent on to the land line phone company the switch will send a message to the cell site assigning it a voice channel and you will then start hearing the ringing on the other end. Once the other party answers there is a message sent back called a “OFF-HOOK” signal and that triggers things on the switch for billing to start and such. When the call ends there is a “ON-HOOK” signal sent that stops billing.
Keep in mind all this happens in just a few seconds. It’s happening during that quite time you hear on the phone before you hear any ringing. If the messaging gets slowed down for some reason, it causes the customer to hear quiet longer than they normally would.
This is a very basic overview of call processing on a Mobile Phone system. Hopefully after this you have a better understanding of what is taking place with your phone and what it means when you make a call.
After more than 20 years as a Switch Engineer and part owner for a major wireless carrier, I still find the most common question I am asked even though I am retired is “Why Don’t I Have Cell Phone Service”. This is really not a very difficult question to answer once you have the understanding of how cell phones work and the different carriers you may have service through.
First let me explain that there are two major types of Digital Phones. One is CDMA which is the main service carriers like Verizon and Sprint use and then there’s GSM which is what AT&T and T-Mobile use. There are a few others but they are not as widely used in the industry at this time. These two digital technologies operate totally different from each other and are not compatible with each other. In other words at this time you cannot use a Verizon phone on a AT&T system and vice versa.
Now let’s say you are standing next to your friend and he has phone service and you do not. Most likely one of you has a CDMA phone and the other is a GSM phone. Let’s say Friend “A” is on AT&T and Friend “B” is on Verizon. Since these digital technologies are not compatible at this time then it would require both carriers to have a Cell Site system in the general area as to where you are. Keep in mind in a perfect world (Flat with no trees) a cell site will talk on average about 20 air miles. So you will both need to be within that distance to the cell tower. As we all know it’s not a perfect world so expect anywhere from 10 to 15 miles in Rural country and up to 5 miles in Urban. That is the basics of the causes. Now let me explain why there isn’t always a tower where people think there should be one.
Below I will be listing some numbers. These numbers are for reference only and will be adjusted by each carrier based on their business model. But the numbers I use are very close to what they may use.
First thing that will determine if a carrier places a cell tower in a general area is how much revenue they can generate and what is the total payback of the site. This means how many calls will be made and how many years it will take for the site to break even between build and maintenance costs and revenue. On most systems they shoot for a 24 to 48 month payback. They also look at things such as population and road traffic. They will need to see if they can get on average about 2000 customers in the area. Thus based on the population and the number of other carriers in the area this can become quite difficult in small populated areas. The Average cost for a cell site is about $750K. This includes everything from a tower to equipment and man power to get it up and running from scratch.
Let’s say a carrier can now justify a tower in a particular area. The next biggest hurdle they run into is local governments and the citizens themselves. Everyone wants Cell Phone service but no one wants a tower in the area where they can see it and take away from their view. Most people want their cake and eat it too. Also a lot of local Governments have instituted a ban on new towers and thus this makes it even more difficult. Then of course you have things like the FAA if you are near an Airport.
If for one of the above reasons a carrier cannot put a tower up where they would like. They now are forced to co-locate on another tower in the area. This is being done more and more but this also causes other issues. The higher on the tower you place the antenna’s the better coverage you can get. Thus, the first one or owner will usually get better coverage. If one carrier has to share a tower with another, this means that the first carrier will have an advantage over the other. Thus making it hard to get customers the service they want and expect. Also, if they are competing against each other, the one carrier that owns the tower can make the lease so high that it takes the second carrier beyond their justification for being in the area to begin with. In other words carrier “A” can make it too expensive to compete against carrier “B” in an area.
Now you see why one person can have phone service in an area and another doesn’t. This is why it’s important for the consumer to look at where they want their phone to work before they sign a contract with a carrier. Most places, if Carrier “A” isn’t there and Carrier “B” is, you may have a chance to roam but then Carrier “C” must be using the same digital technology that you have for it to work.
Have you ever wondered why your local wireless carrier has placed, on your phone bill, so many roaming charges? In this day and age, customers want to be able to make and receive calls worldwide with little to no effort. There are many things that go into allowing this, at the same time being seamless to the end user while traveling.
Before we get into this article too deep, I feel you should have an understanding of a few basic terms I will be using. There are not many, but these are the cornerstone to how everything works together smoothly.
HLR: Home Location Register. This is a database on your home carriers system that stores everything to know about you and your phone. Some of the things it keeps track of are; Serial Number, Phone Number, and features you have paid for. It also tracks where you currently are which I will explain a little later on in this article.
VLR: Visitors Location Register. This is a database that holds the same information as the HLR but is located on a visiting carrier switch and not your home switch. It also keeps track of where you are but in more details than the HLR.
SS7: Signally System Number 7. This is a protocol that wireless carriers use to talk between each other in order to pass information. It is used for a lot of different messaging, but for this article it is used to talk between HLR’s and VLR’s.
STP: Signaling Transfer Point. These are systems that are used to transport the SS7 Protocol between HLR’s and VLR’s among all wireless carriers.
Now let us start with what happens when you first arrive into a new system by either powering on your phone or by driving. Without you even knowing it, your mobile phone will send a message to the roaming carriers system telling it that they are in the area and would like to be able to use their system. When this happens it, initiates a message from the VLR to its home HLR to gather information on this customer so that when it’s time to make a call it has the data needed to offer the service. It will store this information for a given amount of time determined by the HLR or till the customer drives to another carriers system.
Now, when you go to make a call, the VLR has all the info it needs and process the call based on your feature plan. Nothing fancy happens here. The big issue is when you want to receive a call.
When someone goes to call you, they obviously don’t know exactly where you are and who’s system you are on. If coming from your house, the call is routed by the phone company to your homes system based on your 10 digit phone number. The first thing your home switch does is it looks in the HLR to see if it knows where your phone is currently located. It will have this information, because, when the VLR requested it the HLR logged the info for just this reason. The HLR will see that the customer is being serviced at this time by another carriers system and will forward a message to its VLR stating this customer has a incoming phone call. The VLR will then check its database to verify that they do indeed have the customer on the system as it tracks where exactly the customer is located and will then assign what is called a TLDN. This is basically a temporary phone number that it assigns to the customer for the purpose of receiving the call. The TLDN is forwarded back to the HLR and it in turn forwards the incoming call to this number. That call will then route to the visiting system switch and on to the customer’s phone. Once the call is answered, the TLDN is release by the system so that other customers have it available to receive calls also.
As I was mentioning earlier in this article, HLR’s and VLR’s transfer their SS7 Protocol messaging between each other via nationwide STP’s. These STP’s are systems that third party companies maintain and operate. They operate links to all carriers worldwide. The purpose of these companies are to avoid carriers from having to have links to each company as that can get costly and messy. You hook up to these companies and they have the links in place and just route your messaging for you. There are a couple major companies that offer this service, they are VeriSign and Syniverse. Other companies exist but these are the most popular ones used. These companies also have links to each other for talking to those companies that are with the other. This makes the whole world one big happy messaging link. All carriers have to do after this is sign roaming agreements with a carrier and then notify these STP companies and have them open up the messaging between the associated HLR’s and VLR’s.
In closing: Whether your internationally roaming or just going down the street to your friends. Whenever you leave your home market you could entail roaming changes. Hopefully this article helps explain why those costs are in place. Wireless roaming is a major concern to carriers since latest price plans have started offering it free. Nothing is free in this world, therefore, each call made or received while roaming does ultimately cost the carriers just in messaging costs to STP’s.
There are many things to consider when choosing a wireless provider for all of your personal and professional needs. A wireless phone has become a great part of our daily lives, more than any other technological device to come along in quite a while.
1) Monthly Price Plans
3) Phone Types
4) Roaming Fees
5) Contract Terms
Monthly Price Plan:
Anymore, the monthly price plan has almost completely been turned into a non deciding factor in choosing a wireless provider. You can almost always find that each carrier in your area has the same offers when it comes to the number of free minutes for each varying price plan. The things that vary and you need to pay more attention to are the add-on’s that the carrier uses to make the plans different. These add-ons include things such as voice mail, SMS/texting, and amount of data in MB that you can upload and download without occurring additional charges.
In this determining factor, you have to look at your daily routine. Where is it that you want to be able to send and receive messages or calls? If you are someone that travels frequently, then you need to see which cities you spend a lot of time in and if that carrier is located in that town. Even if they are not your phone will still work but you may incur roaming fees that I will discuss later on in this Hub.
This is more of a personnel decision for you to make. Most people go for physical looks, but you need to make sure it has the functionality that you are after. Look at things such as the keyboard layout, is it comfortable to use, also will it surf the internet if you need it to. Some of the flashy phones are also very fragile. You need to look at your daily routines and make sure that the phone you have chosen can hold up to the beating it will endure while you care carrying it. Also when using the phone to chose your wireless provider, you have to take into account that there are two types of digital phones. One is GSM and one is CDMA, these two technologies will each have different phone models to choose from. The phone you most like may not be available with the carrier you choose due to the digital technology differences.
Many carriers are eliminating these charges and including them in their monthly fees. However, there are still some instances where these can be applied to your situation. Also, there are still some price plans that don’t include free roaming in there offer. These charges are applied when you travel to other locations that your home carrier doesn’t serve. In this situation you are actually using some other carriers system and they in return charge your home carrier a fee for you to use it.
With the exception of pre paid phones, every wireless carrier will have some sort of contract with various terms for you to agree to. If you find yourself wanting to get out of these contracts they can be very costly. The purpose of these contracts, are to allow the carriers to re-coop their costs for the phone that they either gave you for free or at a discounted price when you signed up. This is the reason many chose to use a prepaid phone, however, with those you end up sacrificing other important features you may have wanted.
Wrap Up. There are numerous things to take into consideration when choosing a wireless provider. You need to look at the entire picture of what you need and not just their advertised monthly fee. If you chose the wrong carrier for your needs, you could get caught in a long contract with high fees to cancel, thus forcing you to stay with a carrier even though you are not satisfied with their service.
One of the most expensive thing for International travelers or just people that are just going on a short vacation are the wireless roaming charges you will incur when outside your home country. There are many ways to try and keep International roaming charges to manageable levels but only if you pay attention to how you are going to use your wireless phone.
The first obstacle you will have when traveling with your wireless phone is the obstacle of just making sure it will even work at your traveling location. Until LTE becomes more of a deployed system worldwide there are only 2 basic types of digital technology that phones and wireless carriers use in their networks.
CDMA: This is the digital technology that carriers such as Verizon and Sprint chose to use in their home markets.
GSM/UMTS: This digital technology is used by AT&T and T-Mobile type carriers. These phones are easily identified because they use something called SIM cards that store all your phone information on them. The SIM card can be located behind the battery.
World Phones: This phone is a combination of these two digital technologies. They became popular a few years ago and have grown drastically especially among travels. This phone will actually work on both technologies. It will first prefer the home carrier type of digital technology and if it is not able to locate a compatible system it will fail over to the other.
The main issue when using CDMA or UMTS only phones is that in many countries and remote vacation islands you may only have one carrier operating there. When that is the case you phone may or may not work pending if the local technology is compatible with your phone. This is why the World phone has gained popularity over the years with travelers, as it eliminates the one major obstacle you could run into.
Now that you have arrived at your foreign location and you do have wireless service with the local carrier, it’s important to try and keep your costs down as international roaming fees can be very expensive. Always check with your phone carrier to get accurate costs before you travel. Some carriers will offer an international roaming feature for your phone. This is especially true for those that have world phones.
If you are using a world phone or a smart phone it should be WiFi capable and this will be the best method for you to keep the costs down. Almost every hotel and even some restaurants offer free WiFi to its guest. If this is the case where you are traveling, all you have to do is put it in WiFi mode and that will allow you to make a Voip call at no cost to you at all. If you travel a lot to a location that doesn’t offer free WiFi but does offer free data service in your hotel then take along with you a Wireless router and turn the hotels data connection in your room to a WiFi signal and that will allow your phone to lock on it for use. This last method is actually the one I use when traveling so I can keep in touch with my daughter back in the states for little to no costs.
Another way to save money when international is with your Text Messaging. This can also be very costly if you tend to do this instead of calling people or emailing. Most international areas charge you as much as 50 cents per text message you send. Your text messaging service you have at home, so many messages for a flat fee, doesn’t apply when roaming internationally. There are new App’s available for smart phones that allow you to send and receive text messages without actually using the text option on your phone. If you are again on a free Wifi system you can use this App and not pay the international roaming charges. The only downfall to this is that you must have some kind of Smart Phone that allows you to use the Apps.
In closing, let me say that there are many ways to keep your costs down when traveling internationally. You just need to do a little planning and thinking it through before you go there and receive your wireless bill from your visit upon your return home. There is one method that I have not listed here and this method is only usable by the person traveling on vacation. That method is to just plain turn your phone off and enjoy your vacation. If you are with the family, like you should be, there is no reason to need to call anyone anyway. Enjoy and Relax, you don’t get to travel internationally very often most likely. You are likely in a very nice location that you want to enjoy and savor the memories.
First let me start off by saying that I do not write these articles about the Wireless Phone Business to defend the carriers and the way they operate. I would be the first to tell you that from my experience in the industry for many years running one of them, that it is a business like everything else an it’s all about maximizing rate of return on investment when it comes to customers and charges.
I get asked a lot from people when they learn who I am, as to why when they switch from one carrier to another they usually have to purchase a new phone? This is actually a very simple answer but I will need to explain in more detail how a phone or data device works for you to understand.
First thing you have to understand that until everyone goes to LTE technology, that there are basically two types of Digital systems made in the wireless industry.
1) The first is CDMA which is the technology used by such carriers such as Verizon and Sprint
2) The second is GSM/UMTS which is the technology used by Carriers such as AT&T and T-Mobile
The first reason you can’t move your phone is probably the most obvious to people, that is that if you are moving from one digital technology to another, the phone will not be designed to work on the other carriers technology.
The second reason is actually the most complicated to explain but I will try and list it all for you. This would be the case if you were moving from a CDMA carrier to a CDMA carrier or the same for GSM/UMTS Carriers.
It all comes down to the programming of the phone itself. There are so many parameters that go into the programming of a cellular phone to make it work the way customers are accustomed to. This includes things such as to how to do run applications like SMS, MMS, and WAP. Each one of the applications in the phone requires certain programming to match the carrier’s equipment. This includes things such as DNS server IP addresses, how often the phone scans for a stronger signal, the max size of a picture to be sent via MMS, and things along that line. These are all settings that are installed in the phone in what is called a PRI file.
Many of you may have heard of a PRL file, which is where the phone gets its roaming list from as to who the phone can roam on and who it cannot. But actually the more important file is called a PRI and that is what tells the phone how to operate in general. This has become even more complicated of a file since the introduction of data aps and the internet.
You will see all over the internet in forums about people unlocking or hacking a phone. 90% of the time this is just enough to allow you to change the phone number or the data address of the device, most of the time doesn’t unlock it enough to allow someone to change the entire PRI. Unlocking a phone usually just allows someone to use a tool called QPST or CDMA Toll that can go into the phone and change particular parameters that will allow you to make phone calls or surf but doesn’t actually allow you to change fields used for MMS and WAP and certain other applications.
To truly change the PRI for a particular vendor phone you have to have flashing software and tools. Almost every manufacturer of mobile devices has their own version of the QPST for doing that. To get that software you usually have to be a seller of that manufacturer or a carrier before it is totally shared with you.
As you can imagine a carrier is not going to have this software available at all sales stores you may go into to sign up for service. A company may only have 1 or 2 copies of this software and that is just for testing in there lab the different models of phones and how they operate in different scenarios.
Also not all phones are alike, some of the major carriers will actually put each phone model through extensive testing on their network to make sure it meets certain criteria. There are some models of phones that may drop more calls than others because of the way the antenna is built into the device. They won’t allow these models on their network because it just opens up the opportunity for customers to start calling and complaining about the service, when it’s actually the device they are using not the service. This is very expensive for most carriers to perform so you will find only the major carriers will have test labs..
Even with the emergence of LTE and the fact that all carriers will eventually go to LTE, This technology doesn’t support voice calls as the average consumer thinks of it. Voice calls will actually be made over a data application and in order to perform these functions there are even more detailed requirements that must be put into each phone based on the home carriers system. LTE does solve the problem of different digital technologies on different carriers but the other issues will still prevail.
So as you can see there are some technical reasons why a carrier will not let you bring a phone from one carrier to another carrier. It’s more about the phone itself and the programming of it than it is about the carrier wanting to sell you something new. I agree, it’s very frustrating as a customer to have to purchase a new phone if you are changing carriers. Again, you can hack them and unlock them to allow you to do the basics, but you still can’t expect a carrier to do that for you due to time and effort. Even the IPHONE when it is hacked into the only real data most people can get is via Wi-Fi and not 3G.