PHP web application + TAPI / VOIP telephone calls?

A client wants to use our (ERP) web application as some kind of开发者_运维技巧 incoming and outgoing calling software. He needs phonenumer recognition and to be able to dial a number by clicking with the mouse and then pick up his phone.

Somehow a TAPI or VOIP connection must be made on the clients computer, I think... for this I could create a small listener/dialer program (not in PHP, but in Delphi for example) that is installed on each client,but how would I let this communicate with the browser / web server?

Another way could be by installing our web application on the server of the client itself, which has a direct link to the telephone software server.

Has anybody ever done something like this in PHP ? Any suggestions?

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Is your ERP software written in php? You may want to integrate with Asterisk (and open source pbx) (and by extension FreePBX if your in php anyway)

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I came across this site www.tropo.com which has an API that adds Voice and SMS support to PHP and other languages.