Hello, We have wide area experience in VOIP and IVR open source technology like Asterisk, Zaptel and SIP Protocol configuration. If you like we can send you our previous project details.
Beside this we have expertise in the php/c++/linux/so files/fusebox AND WINDOW based ASP,COM,DCOM,MTS,VB,VC++,.NET.
Please forward me your mail ID so i can forward you project proposal according your current requirement.
SG