Phone dialer built around a microcontroller

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phone dialer litelink

I need to make a DTMF/pulse dialer, and I can't find dedicated chips here, so I'm using a microcontroller. What I want to know is what are the electronics for interfacing a microcontroller to the phone line. Can someone help me?

I would also like to know where can I find a reliable description about how the line states are signaled on PSTN's, and all the necessary details for making a basic simplex modem around a uC.

I repeat, dedicated solutions are not an option because of the poor avalability of such chips.

Thank you.

PS: sorry for the double post, I didn't know what is the most appropriate section
 

Hi

For Europe, the phone line characteritics are described in the ETSI recommandation EN 300001.

If I do remenber well, you can download it for free on the ETSI site at :

h**p://www.etsi.org/services_products/freestandard/home.htm

To build an interface, you can used dedicated module like those from CLARE :

h**p://www.clare.com/Products/LITELINK.htm

or you can build your own interface with discret components. Here is a link to some schematics:

h**p://www.hut.fi/Misc/Electronics/circuits/teleinterface.html


* = t
 

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