hi,
I have a vast experience (around 10 years )in Asterisk application development using both PHP and VB.net, I have a very good experience of almost all asterisk flavors including elastix-MT.
This project will need to have few parts for the gui ,
1) PBX Admin gui , which will be used by PBX owners to create customers and allow the customers access to Customer Admins,
2) Customer Admin will allow the customers to create extensions , IVRs , buy/assign DIDs ,etc.
3) User GUI which will allow each extension user to access voicemail, send fax, manage contacts, call forward etc.
I think we will need to discuss the project thoroughly before we start,
Kindly let me know what time is good for you to discuss the project,
Regards,