[asterisk-users] Different click2call?

[Darko]

Hello List,

We are deveoping apication/system based on PHP5, Postgre,Ajax,ect..
It should be compleate sistem for realystate agensy and road worers(agents)
and it will be distributed system.
We made very good inplementation based on asterisk and OSP for distributed
offices and it will be part of system (integrated).

We would like to implement some options in system:
Agent have  contact list with phonebook (clients and sellers of
proprieities) in aplication, agent have hard IP phone or dual-mode phone.
The Idea is when he/she click on number in contact in aplication, number
shuld be forwarder to asterisk and if is connected to other side agent phone
will ring.
If call faild asterisk should informe agent that ather side is busy.

Please can anyone give us BEST IDEA HOW TO develop this?

Sorry for my English

Best regards

Darko