In the Relay mode, the firmware on the device detects fax, modem, or TTY tones. To process the call over the IP network, the firmware uses the appropriate modulation protocol for fax or modem, or Baudot transport representation for TTY. The modulation and demodulation process for fax and modem calls reduces bandwidth use over the IP network as compared to the Pass-through mode. The Relay mode improves the reliability of transmission. The correct tones are regenerated before the calls reach the destination endpoint.
Note:
Do not use Avaya-proprietary fax and modem relay protocols. For modem relay applications, use the V.150.1 modem relay protocol. For fax relay applications, use the T.38 fax protocol.
