Litecom provides support of many VoIP Systems and equipment.
First let us say, while there are many blogs discussing the ways to fix VoIP, it just is not true. Think of it as trying to self diagnose a medical condition. It's just not going to happen unless you visit the doctor.
Services include but not limited to:
Auto attendant configuration
Trunk Provider setup
Inbound / Outbound route configuration
Dialing Plans and Translations