# PBX Support

Interfacing the RTU to a PBX or PABX phone systems can occasionally present problems. Some PBXs have a non-standard dial tone. Additionally, in many PBXs, you must first press a special key, like a '9' to get an outside line. After pressing the '9' there may be a short delay followed by the dial tone for the outside line. Entering a comma for each one-second delay desired will configure the necessary dialing delays.

Note: By turning OFF CPM you can avoid problems with non-standard dial tones from your PBX system.