How connect GSM (cellular-phone) to microcontroler, reading dial-tones and dial a phonenumbers?

Ericsson and others make GSM nodules, with an RS232 port and the guts of a mobile phone inside. You can plug in a microphone & speaker for analog, but you can also do all the digital stuff through RS232 - dial numbers, answer calls. You can also go on the internet, do Text Messaging do Data vs Voice calls. Have a look at websites of phone companies for specs and info. I have a feeling that some mobiles can do this via a connector. The modules aren't too expensive.

A disadvantage of phones is you have to pay to keep a phone on the network, just to wait for the message to unlock your door. There are short range RF modules available which will interface to your microprocessor.

Roger

I'd look at hacking one of the X10 TR16A touch tone controllers below. It answers a phone call, and can decode touch tones. Once it goes off hook, you probably could talk/listen to people at the front door via a handset or mic/speaker attached to it. Probably a lot cheaper than trying to use a cell phone.

Are these devices and services available in the US of A ???

Did you consider using a bluetooth enabled phone?

What way you could use the bluetooth interface to program the GSM phone.

Deepa

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But calling without answering doesn't cost anything! ;-)

But calling without answering doesn't cost anything! ;-)

Yes I have, but there no simple way to use bluetooth with a microcontroller-chip like Pixace. Is there?