Help Me Figure Out if My Phone is a Boy or a Girl

August 1, 2006 2:53 PM

Cingular has announced it will now charge all customers not using a GSM phone $5/month, beginning in September. How can I tell if my (several years old) phone is GSM? I'd ask the nice people at the Cingular store but suspect they will be too busy plying me with new fancy phones to give me an honest answer.
posted by foxy_hedgehog to Technology (20 answers total)

Does it have a SIM card? If yes, it's GSM. If not, TDMA. If you post the make & model someone could probably tell you in a couple of seconds.
posted by GuyZero at 2:56 PM on August 1, 2006 [1 favorite]

Response by poster: Wow- if only I'd known it was that easy. Thanks!
posted by foxy_hedgehog at 3:32 PM on August 1, 2006

Another way to know is to simply take the barrery out. If you see a little card that slides into a slot, your phone is GSM.
posted by nathan_teske at 3:36 PM on August 1, 2006

I, too, have an ancient phone that will get hit with this upgrade.

My fear is that whatever new phone I might get will have this annoying technology they're building in, something relating to 911 calls and being able to find someone's location. Sounds a little paranoid, I know, but you can't be too careful. Phase II compliance with the FCC law enables them to pinpoint you to within 50-300 meters. Ack!
posted by adipocere at 4:02 PM on August 1, 2006

GuyZero: my phone (Nokia 3560) has a SIM card but Nokia lists it as TDMA. So SIM doesn't seem to be synonymous with GSM ...
posted by mmw at 4:05 PM on August 1, 2006

OK, folks, how about let's get a bit more precise about our jargon here?

There are three kinds of cellular air interfaces, which are known as Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and Code Division Multiple Access (CDMA). Each of the three is used by multiple, incompatible systems, but FDMA (which was used by AMPS) is obsolete and has been phased out in most areas.

TDMA is also obsolete, and the industry is in the process of phasing it out now.

GSM uses a TDMA air interface. So does IDEN. And so does IS-136. When most of you use the term "TDMA" you're probably thinking of IS-136, but in fact all of IDEN, GSM, and IS-136 are TDMA.

IS-136 was used by the AT&T cell system, which was eventually absorbed by Cingular. IDEN is used by NexTel.

Right now, for historical reasons, Cingular has three different and completely incompatible standards deployed in different geographical locations: IS-136 (TDMA), GSM (TDMA), and UMTS (CDMA).

UMTS, like IS-95, J-STD-008, and CDMA2000, uses a CDMA air interface. IS-95 was the standard Verizon originally used, and J-STD-008 was the standard Sprint originally used. Both of them well advanced in the process of switching to CDMA2K.

So what systems can any given phone talk to? That's where it gets complicated, because multi-mode phones are becoming more and more common. UMTS and CDMA2K are incompatible (deliberately; the Europeans refused to use the same chip rate that CDMA2K uses because they wanted the systems to be incompatible) but there are phones out there designed to work with both systems anyway.

And it turns out that UMTS phones have sim-cards, even though UMTS is incompatible with GSM.

Why the fee? The simple answer is that Cingular wants its GSM-using customers to toss their phones and buy UMTS phones instead. As long as a substantial proportion of Cingular's customer base keeps their GSM phones, Cingular can't scavenge the frequencies they're currently using for GSM to be used for UMTS. Unlike the IS-95-to-CDMA2K upgrade, the switch from GSM to UMTS requires a clean break. (IS-95 phones work with CDMA2K base stations, and CDMA2K phones work with IS-95 base stations. Neither of those is true for GSM and UMTS.)

The fact that you have a sim card doesn't tell you anything. You can find out if you're going to get stuck with that fee by looking at your next bill, or you can look up your specific phone model to find out. What you want to look for is the specific protocol the phone is designed for: either IS-136, or GSM, or UMTS.
posted by Steven C. Den Beste at 4:25 PM on August 1, 2006 [4 favorites]

OK, I read your post slightly wrong. It looks like what Cingular is trying to do is to get its customers who are using IS-136 to toss their phones and upgrade to GSM, rather than getting GSM customers to upgrade to UMTS.
posted by Steven C. Den Beste at 4:31 PM on August 1, 2006

I wish I could buy a cell phone only for TALKING; ie, without cameraphone and any other apps that I don't need, want or use. Oh, to return to my Motorola StarTac from about 2000.
posted by aacheson at 11:26 PM on August 1, 2006

Yup, Cingular/AT&T is trying to get rid of their old TDMA / IS-136 installed base. They're pushing GSM phones as a replacement. (Nice thing about this is that many of the foreign GSM phones will work on the American frequencies, so you have a wider choice of phone hardware.)

As SCDB points out, many air interfaces are "time-division multiple access", but in the cell phone context, the abbreviation "TDMA" always refers to IS-136.
posted by hattifattener at 12:32 AM on August 2, 2006

So is the US system more advanced or less advanced than the European?
posted by A189Nut at 5:53 AM on August 2, 2006

So is the US system more advanced or less advanced than the European?

The European system has been working better than the US system for more than a decade. CDMA-based systems theoretically make better use of available bandwidth, but the European market is so much more mature that bandwidth efficiency is hardly enough to put the US ahead.
posted by GuyZero at 7:45 AM on August 2, 2006

This news report makes clear what's going on (even though it mangles the technical terms, too).

They're trying to force IS-136 and AMPS users to get GSM phones so that they can scavenge the spectrum currently being used for IS-136 and AMPS. This is part of the process of "absorbing" the AT&T acquisition. (Though it's more like "You will be assimilated" from the look of it.)

GuyZero, don't start with me. CDMA-based systems can carry 2-3 times as many calls per unit spectrum as TDMA-based systems, and CDMA-based systems can dynamically allocate bandwidth per customer, which TDMA cannot easily do. As a result, CDMA-based systems can carry high speed digital using the same spectrum as it uses for voice, whereas when GSM wanted to roll out high-speed digital (though it was more like medium-speed) they had to cut off and dedicate spectrum only for that function.

There's a reason why GSM abandoned TDMA and switched to CDMA for their 3G systems. Everyone in the industry knows that CDMA is superior to TDMA.
posted by Steven C. Den Beste at 11:07 AM on August 2, 2006

my phone (Nokia 3560) has a SIM card but Nokia lists it as TDMA. So SIM doesn't seem to be synonymous with GSM

You probably have the GSM version, the 3595.
posted by cillit bang at 12:08 PM on August 2, 2006

but FDMA (which was used by AMPS) is obsolete and has been phased out in most areas

Actually, no. All radio systems use FDMA, even those that also use CDMA or TDMA, so it's not worth mentioning.
posted by cillit bang at 12:13 PM on August 2, 2006

There's a reason why GSM abandoned TDMA and switched to CDMA for their 3G systems. Everyone in the industry knows that CDMA is superior to TDMA.

Which I think I stated. My point was that the entire mobile phone system, from a user's point of view, is more than just the air interface. Even with a less efficient air interface, the European GSM system works better than the US system. Phones can be moved easily between providers. International roaming is seamless and relatively cheap. There's a huge selection of handsets, all of which work with every network. There is a wider array of network features. There is a larger variety of services available over SMS. To me, these are the signs of a superior system.
posted by GuyZero at 12:33 PM on August 2, 2006

GuyZero, don't start with me. CDMA-based systems can carry 2-3 times as many calls per unit spectrum as TDMA-based systems, and CDMA-based systems can dynamically allocate bandwidth per customer, which TDMA cannot easily do.

Full Disclosure: SCDB used to (and for all I know, may still) work for Qualcomm, the first major commercial exploiter of CDMA in the US.

Full Disclosure: I, too, think that CDMA (which is actually direct sequence spread spectrum, combined with, as Cillit Bang notes, multiple channels) is a *much* better piece of engineering than any of the TDMA systems *or* iDen; I'm glad that (as far as I can tell) Sprint is retaining it, and will be using it under qChat as they absorb Nextel.

Steven: qChat seems to be *awfully* hard to learn anything about; do you have any pointers you're permitted to discuss in public?
posted by baylink at 3:59 PM on August 2, 2006

It's been several years since I was employed at Qualcomm, and I haven't been trying to keep up with the industry. I've never heard of qChat so I can't help you with that. (And I think it's a bit raw to refer to Qualcomm as "exploiting" CDMA, since they invented it and own the patents. That's how the game is played, and they're playing it by the rules.)

Cilit Bang, "FDMA" is a term of art with a specific meaning and doesn't apply to the way that different users are allocated different frequencies by a regulatory authority on a multi-year basis. It refers to systems in which different frequencies are allocated to specific users on a minute-to-minute basis by the licensee for exclusive use.

It is not correct to say that CDMA is a specialized version of FDMA, because no user ever gets exclusive use of a carrier frequency in CDMA.

The term of art "FDMA" is specifically defined to be mutually exclusive with TDMA and CDMA because it's used to refer to systems which do not use TDMA or CDMA. If it had the generic meaning you think it has, it would be useless as a technical term.
posted by Steven C. Den Beste at 5:23 PM on August 2, 2006

GuyZero says: Even with a less efficient air interface, the European GSM system works better than the US system. Phones can be moved easily between providers. International roaming is seamless and relatively cheap. There's a huge selection of handsets, all of which work with every network. There is a wider array of network features. There is a larger variety of services available over SMS. To me, these are the signs of a superior system.

Most of those are either questionable assertions, or obsolete, or don't apply to the US. You can't move GSM phones between service providers here because they're "subsidy locked". (That's true for phones from other service providers, too.) European GSM phones don't work in the US (and vice versa) because Europe uses 900 MHz and 1800 MHz for cellular, while the US uses 800 MHz and 1900 MHz.

The number of network features for GSM was at one time more varied and rich, but these days CDMA2K and UMTS are the kings of that kind of thing, and CDMA2K really deserves the crown because it's much more built out than UMTS is so far. (UMTS presumably will catch up in the US eventually, but it's mostly going to be a question of whether Cingular wants to match the capital investment that Verizon and Sprint have made.)

And with that we have strayed seriously from answering the question, which violates the rules for askmefi, so I won't post any more about this stuff.
posted by Steven C. Den Beste at 5:28 PM on August 2, 2006

Nice thing about this is that many of the foreign GSM phones will work on the American frequencies, so you have a wider choice of phone hardware.

There are multiband phones designed to use both American frequencies and European frequencies, but what companies like Nokia usually do is to bring out a new model in multiple versions which differ only in the RF final stage. The cases and features will be identical and usually the model numbers will be very near to one another, but won't be the same. Which means that for any given European phone there's usually a version for the American market, but it's not usually the case that the exact phone used in Europe will work in the US, unless it is specifically designed to do so.
posted by Steven C. Den Beste at 6:26 PM on August 2, 2006

Certainly, Steven; I didn't mean to diss Qualcomm; they're some of my favorite people.
posted by baylink at 6:49 PM on August 2, 2006