Nov 19, 2007

Choosing a cellphone and carrier

The time has finally come for me to crawl out of the dark ages and get a cellphone. But what a rat’s nest this is!

GSM, or CDMA? Do you want AMPS with that? How about TDMA? Oh, and if you want some data, how about WCDMA or 3G?

GSM (Global System for Mobile Communication) is a open standard for mobile phones which is widely used in the rest of the world (especially Europe and Asia). It’s based on TDMA. The advantages of GSM are that there are more cool phones, you can easily switch phones (as long as they are unlocked) by swapping your SIM card, and data service is readily available.

In the US, Cingular (including the recently merged AT&T) and T-Mobile use GSM networks. Cingular/AT&T have more coverage than T-Mobile, but T-Mobile has better plans. Cingular’s network uses the 850MHz and 1900MHz spectrum whereas T-Mobile is exclusively 1900MHz; 850MHz gives better in-building reception, so if you want to go GSM, Cingular seems to be the best choice (Cingular and AT&T are actually converting away from an older digital technology, TDMA.)

CDMA is a technology developed and owned by Qualcomm (no open standards here), which works in a different way to TDMA. It has technical advantages over GSM, in that networks can have a higher capacity (at the expense of voice quality), but is not necessarily technically superior. Also, some CDMA phones also include analog (AMPS) capability (more of which in a minute).

In the US, Sprint and Verizon use CDMA networks. Sprint uses a 1900MHz spectrum (again, poor for in-building reception), and Verizon mostly uses 800MHz CMDA, which gives better reception. So, if you want a CDMA phone, go for Verizon.

There is a third, older form of “cellular” technology, AMPS (Advanced Mobile Phone System), which is an analog system that has much greater coverage than the digital networks (GSM and CDMA). AMPS is used by road-side emergency phones and GM’s On-Star system, but it’s being phased out. However, if you want coverage in rural areas where the digital networks don’t reach, then you want a phone with analog capability, which really constrains your choice of phones. No GSM phones support AMPS, so if you want analog, you have to go for CDMA.

If you are now totally confused, here’s a table which summarizes the repercussions of the technological issues.

So, after digesting all that, I figure that I’d get the best coverage and reception from Verizon with a 850/1900MHz phone with AMPS capability (aka analog roaming). Looking at their phones, the Motorola V710 is one of the few non-sucky phones with some hope that it might be able to sync on Mac OS X over iSync. Furthermore, the V710 has analog roaming.

However, what Verizon don’t tell you is that the V710 you get from them is crippled. They turn off a bunch of features on the phone (like Bluetooth OBEX object exchange) so that you have to use their pay-per-use services instead. Oh, and they just discontinued the V710, replacing it with the E815 which doesn’t have analog. Great.

So, maybe I should look into Cingular/GSM. The choice of phones is certainly much greater, and may more of them are iSync-friendly.

permalink | computing/equipment | 2007.11.19-22:33.00