“Extension” - is the extension of the telephone line (PBX) or the Centrex system. It works as an association and allows calling to certain telephone sets without the necessity of dialing the telephone number, but only by dialing a short combination of digits, reaching the desired subscriber.
PBXMate software Sip Trunk for improving Audio Quality. Removes noise originated from external mobile phones or from the call center, keeps audio level at a comfortable level and removes echo.