TELECOM Digest OnLine - Sorted: Re: When is TDMA Being Phased Out?

Re: When is TDMA Being Phased Out?

Jim Burks (
Thu, 01 Dec 2005 01:38:52 GMT

<> wrote in message

> Could someone describe what is "TDMA" and "GSM" in layman's terms? I
> presume these are communication protocols and are not compatible with
> each other. Is one analog?

TDMA, GSM and CDMA are all digital cellular standards, concerning
signaling, call control, etc. None of them are compatible with each
other. All of them work on various frequencies (800, 850, 900, 1800,
1900 mhz) in various parts of the world.

Analog cellular is called 'AMPS'.

Current (old) NexTel uses iDen. It's not used much anywhere else and
NexTel is phasing it out with the Sprint merger. But, it does
push-to-talk really well.

TDMA is being phased out quickly as the Cingular / ATT Wireless merger
goes through, though it is still available in almost every area.

Europe and most of the world outside the US use GSM. GSM uses SIM
cards to carry the subscriber information (phone number, etc.). If you
switch your SIM card into another phone, your number and account go
with it. If you travel internationally, you can also use your fancy US
handset with a local SIM card and pay local in-country rates (but
calls won't be forwarded from your US number).

> Do other carriers (ie Verizon) use them or other protocols? Does
> Verizon have any protocols that are going away?

GSM = Cingular ,T-Mobile, Vodaphone
CDMA = Verizon Wireless, Sprint
TDMA = Cingular, ATT Wireless (legacy)
AMPS = all right now, going away before 2010

Most handsets work on ONE of these protocols. New handsets now are
either GSM only or CDMA only. The are also frequently locked to a
single carrier. The better GSM handsets are tri-band or quad-band
(more frequencies). This will allow them to roam in many parts of the

Older handsets were either GSM / AMPS, TDMA / AMPS or CDMA /AMPS to
use as areas built out digital coverage. Nokia built one line that was
GSM / TDMA / AMPS (all three) for Cingular and ATTws. Verizon offers a
CDMA / GSM combo handset for world travelers, but it's much more
expensive than most, for the same features.

> I guess now there are three big cellular companies -- Verizon, Cingular,
> and VoiceStream? Is Sprint still independent or did they merge?

No, really four: Cingular (with ATTws), Verizon, T-Mobile and Sprint
(with NexTel). VoiceStream either became T-Mobile or was acquired by
Verizon (not sure which).

> I get the impression all three companies are actually a hodgepodge of
> smaller companies they acquired and merged into along the way. That
> means service quality of a particular carrier will vary greatly from
> one part of the country to another, just as landline service varies
> greatly. (In Verizon particularly which is made up of many different
> companies).

Exactly. They also use various frequencies in different parts of the
country. Cingular uses 850 and 1900 mhz.

There are also a number of regional carriers.

Also coming up are MVNOs -- marketing companies without
networks. These include Virgin Mobile, TracFone (pay as you go) and
there are many others coming online in the next 18 months. It will be
like the CLEC expansion. Many names, all using a few networks. Most
MVNOs right now are using Sprint.

Which carrier is right for you?

Glad you asked. It depends on where you live, work and travel.

In the Northeast, Verizon Wireless does quite good. If you travel
internationally, pick a GSM carrier (Cingular, T-Mobile) and you can
roam most places in the world.

If you live in a big city, Sprint and T-Mobile are a little cheaper,
but if you travel out of the cities and off the freeways, you're out
of luck.

If you live in the wilds of Montana or Arizona, look on eBay for a 3
watt analog bag phone. They have MILES more range.

If you stay in the same town all the time, some of the local /
regional carriers offer real unlimited usage (day, night, weekend).

Jim Burks
Memphis, TN

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