Hi,
Just to let you know that I have already developed a custom PBX having features
like
voicemail,
receive vociemail through email,
follow-me
IVR
Wallboard to monitor live calls
call recording (available to download)
There are alot of features. It is a complete custom PBX but it does not contain some of your
required functions like invoices, billing, reseller .... etc
All I want to say is, I have a custom PBX that can be customized to fulfill your requirements that it have and that it does not have.
I can provide you a Free Demo. Please let me know.
Regards,
Aneel