i need copy of AT commands for siemensc35

How about contacting Siemens, or checking their web site? Or check with your local distributor!

See: http://www.keil.com/forum/docs/thread9571.asp

Andy - I know that you always recommend GSM modules.

But remember that it isn't just professionals who ask questions on this board, as should be obvious from some of the posts. Most students and home-designers often specifically want to use a normal phone and not a module for their projects.

The phones can be had for free - there is a huge amount of old phones available.

The modules often have very fine-pitch connectors - unless they are soldered directly on a PCB - and most DIY people don't want to call around to find anyone selling them one or twho connectors. They also need to locate a suitable SIM-card holder.

The pitch of the connectors are no problem for factory production of professional equipment, but a lot of modules are very hard to make use of for people who make their PCB themselves (or make use of prototype boards) and only select DIL or PLCC chips or similar to stay away from fine-pitch components.

The main problem with using a normal phone, is that there is no easy way to turn them on/off, so you may have to do that manually in case the phone hangs, unless the phone supports running with only external power. They also have a bit higher power consumption, since they have front-end logic for the display and keyboard.

However, there is nothing wrong with the actual modem interface, which is the reason that the phone manufacturers do sell data cables for their phones. If a PC can connect and use an external phone, so can home-built equipment.

Most people who get into troubles interfacing with a phone doesn't have problems because they selected a phone, but because they are new to this. It's called learning, and is a good thing. Let people try. Let people learn. Let people make mistakes. Let people grow. Do recommend that commercial project should use modules, and not normal phones. When mass-producing, modules are always the better choice. However, most people who have modem troubles and ask question on this forum is not going to mass-produce solutions. They want to control the heat in their cabin, or get their school project accepted.

What would I use, myself? If I would like to do a quickie, I could fix a data cable and interface a normal phone during a weekend, for almost no cost. If I had a bit more time, I can get a module and some connectors from my ordinary work. But, it would definitely take a lot longer to create a solution - at least for the modules I normally uses, I would need to order the PCB, or request a friend to use a CNC router to produce the board. The problem is: I can't guarantee that when I have the PCB, I would still have the time to finish the project, so my decision would definitely be to use a phone, and get everything done during a weekend. Not beautiful, but working!

"But remember that it isn't just professionals who ask questions on this board, as should be obvious from some of the posts. Most students and home-designers often specifically want to use a normal phone and not a module for their projects."

Quite so - which is why the post I cited also says,
"Having said that, there are plenty of examples on the web of using Nokia phones"

"The main problem with using a normal phone, is that there is no easy way to turn them on/off"

Yes, that's true - but I wouldn't say it's the main problem.

I think that the main problem with using a phone is that the interface is likely to be undocumented and unsupported - they are sold, supported and documnted for consumer use as telephones.

So, if you do want to use a phone, you must be prepared to put in the effort to "reverse engineer" it. The phone may be "free", but this is the "hidden" cost!

A GSM modem or module, on the other hand, is specifically designed for this type of application - with appropriate interfaces, documentation and support.

Used GSM modems are fequently available quite cheaply on ebay.