Advanced Settings of SIP Extension

This topic describes the advanced settings of a SIP extension.

Note: The SIP configurations require professional knowledge of SIP protocol. Incorrect configurations may cause calling issues on the SIP extension.
Table 1.
Setting Description
DTMF Mode Set the mode for sending DTMF tones.
  • RFC4733 (RFC2833): DTMF will be carried in the RTP stream in different RTP packets.
  • Info: DTMF will be carried in the SIP info messages.
  • Inband: DTMF will be carried in the audio signal.
  • Auto: If the device supports RFC4733 (RFC2833), PBX will choose RFC4733 (RFC2833), otherwise the PBX will choose Inband.
Transport Set the transport protocol.
  • UDP
  • TCP
  • TLS
Note: If you change the transport protocol, you must re-register the extension.
Qualify Enable this option to send SIP OPTION packet to SIP device to check if the device is up.
T.38 Support Enable or disable T.38 fax for the extension.
Note: Enabling T.38 will add performance cost. We recommend that you disable T.38.
SRTP Enable SRTP for voice encryption.