Can anyone tell me about the available GSM modems in the market which are AT command compatible.
I have found this and I'm looking for more before I make a move. www.multitech.com/.../
The main thing is I should be able to communicate with it via a microcontroller and therefore I need it to be board mountable(through hole is preferred)
Any help is appreciated.
What do you mean by "AT command compatible"? Note that most GSM modules (it's called modules when intended to mount into your equipment) are using AT commands. But the actual commands supported will differ, since there are no organization standardizing the commands.
In the end, you will have to ignore modules where you can't get a full documentation of the supported command set. The lack of documentation is the most common failure reason for people who are trying to use normal GSM phones.
No, That's not true.
The GSM-specific commands are standardised and specified in the GSM specs: www.3gpp.org/Specification-Numbering
AT Commands in general are now standardised in ITU-T V.250 - see: www.8052.com/.../135933
Of course, there are also manufacturer-specifc commands, and there are manufacturer-specifc variations and implementation details to the standard commands...
Bad expression from me. There are quite a large number of ETSI standards that shouldn't be ignored. But they tend to be a bit "small". And they don't cover all aspects of a module.
When committing to a module, you really do want the manufacturer documentation. Both to get a full description of error codes. But also because the manufacturer-unique extensions tends to be quite important to have. It is often AT commands gets complemented with new commands or new manufacturer-specific commands completely replaces a standard command with extended functionality.
You can manage a lot without the manufactuer-supplied information if all that is needed is to get a non-moving PC to use modem functions.
But when roaming all over the world, the manufacturer-specific extensions can be critically needed. And besides improvements on basic features, a module often has features that are completely manufacturer-unique. The module may have temperature sensors intended to deactivate the transmitter if too high ambient temperatures. It may have AD channels to measure supply voltages. It may have quite complex electronics to support multiple microphones and speakers with different gains and output powers. It may have special power-control commands. Modules supporting user-supplied applications may add a huge number of non-standard commands.
Relying on just the GSM xx.yy standards is quite similar to using a normal PC modem and limiting one self to some old Hayes-compatible subset. You can get a working solution, but might lose a big part of the functionality. The part not covered by any standards may be as big as the part that is covered. And the non-standardized part can be the difference between a truly great product, and a cheap "me too" clone.
Absolutely!
That certainly bears repeating:
you really do want the manufacturer documentation!
you really do want the manufacturer documentation!!
you really do want the manufacturer documentation!!!
In addition to the documentation you must also consider if the modem has been approved for the network it is going to be used on. Makes for an easier certification down the road if that is a part of your release requirements.
A few of the modem providers that are board mountable are Simcom, Motorola, and Telit.
Hope this gets you started...