Using Imported GSM Phones (without 850Mhz) on Cingular
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There has been quite some discussion about whether or not you can use Cingular with a 1900 only phone: here is a little tutorial/FAQ.
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Technically can you do it?
In my experience you can, but it depends. I am in the Boston market. I have friends with 32k SIMs. When I put that SIM into a 1900 phone, it does nothing. When I put my 64k SIM in my phone it shows service. So it partly depends on your SIM, and then it depends on your market. As a rule of thumb: if cingular in your area is 1900, you can use a 1900 phone. This coverage map on Cingular's website shows Cingular's coverage with 1900 MHz only phones: http://www.cingular.com/download/GPRS_coverage_leg.pdf
-AdmiralAK
How do I know what market I am in?
There is a website ( http://www.wirelessadvisor.com ) that lets you search for your zip code and lets you know what frequencies the carriers are running. This website indicates who has a license, it doesnt mean that they are utilizing it!
The Gotcha's!
There is a clause in the cingular contract (don't have the exact wording but if I find it I will post it) that says that Cingular has the right to suspend or terminate your account if you spend a lot of time roaming on other networks examples: T-Mobile and others which run on 1900 and you might not know you are roaming since the carrier logo never changed from "cingular" to anything else.
Also, you will NOT be able to go anywhere on the cingular network where network coverage is indicated to be great because it might be GSM 850, and of course your 1900 phone will not work.
Originally posted by AdmiralAK
Things you might want to know about GSM phones
All GSM phones run on one or more of the following frequencies: 800/850 MHz, 900 MHz, 1800 MHz, 1900 MHz.
Whenever you see 800 MHz OR 850 MHz, they are referring to the SAME frequency range. 850 MHz is more accurate, and has become more commonly used when discussing GSM frequencies. In North America, GSM is run on 850 MHz and 1900 MHz. In Europe, Asia, Australia, and other countries abroad, GSM is run on 900 MHz and 1800 MHz.
Many customers want GSM phones from abroad, or from EBay, to use with Cingular, and attempt to use a phone with incorrect bands. A 900/1800 MHz phone will NOT work in the USA. When looking at a GSM phone to use in the US, you need to look at which of the North American bands the phone uses. In other words, does it use the 850 MHz band? does it use the 1900 MHz band?
Cingular runs GSM on 1900 MHz in some markets, 850 MHz in others, and has a dual band 850/1900 MHz network in others. To find out what frequencies are used in your market, check http://www.wirelessadvisor.com.
If your area is one where Cingular is strictly 1900 MHz, you will have no issues using a GSM phone with just 1900 MHz. If your area is strictly 850 MHz, a GSM phone with 850 MHz is required. In dual band markets, a phone including 850 MHz may be required, or may not be. This depends on whether the Control Channels are running on 850 MHz. The control channels keep you connected to Cingular while not using your phone. If Cingular has Control Channels only at 850 MHz in dual band markets, a 1900 MHz phone will get No Service, as it can not access the 850 MHz Control Channel, even though Cingular is running service at 1900 MHz!!
However, even if the control channels are running on 1900MHz, in a dual band market, a phone with the 850 MHz band will give you much greater reception, as you are able to utilize all Cingular towers. The 850 MHz signal travels further than a 1900 MHz signal, therefore even if all the 850 MHz towers include 1900 MHz, the 850 MHz signal will reach further, and penetrate deeper into buildings.
There are exceptions of course to everything. Such as Cingular offering free roaming on other carrier's 1900MHz signals in a Cingular 850MHz market. However, you should beware that Cingular can turn this roaming off at any point in time. Cingular also has the right to cancel your contract if you are roaming more than 50% of your minutes for 3 consecutive months.
With the buyout of AT&T Wireless, Cingular now has 1900 MHz in almost every market. At the same time, they have 850 MHz in almost every market. Therefore using a phone with only 1900 MHz will really drop your level of service.
When looking to use a GSM phone on Cingular's network, you should first check the bands used by the phone. http://www.phonescoop.com is an excellent resource for this. If the phone is not on the site, chances are very good it does not work in North America at ALL. If it is, Phone Scoop lists the frequencies used. You can always double check at the manufacturer's web site. More and more GSM phones are coming out with the 850 MHz band included.
The only main issue other than frequencies with using your own GSM phone, is whether the phone is "locked" or not. Many carrier's "lock" their phones to be able to use only their own SIM cards. So a T-Mobile GSM phone can only work with T-Mobile SIM cards. Putting a Cingular SIM card in it will give an error. An "unlocked" phone will work with ANY sim card. Therefore to use a GSM phone on Cingular, the phone must be locked to Cingular, or be unlocked. It is possible to buy a locked phone and have it unlocked. However, the simplest thing would be to buy an unlocked phone, or one already locked to Cingular.
Originally posted by Toolhead
