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Advanced - SIP/RTP (Tab) - RTP/RTCP(Section): RTP Keepalive

Phone User Interface

N/A

Firmware

N/A

XML Configuration

<rtp_keepalive perm="PERMISSIONFLAGS">VALIDVALUE</rtp_keepalive>

Description

When a call is put on hold, the phone still sends out a packet through the RTP stream, at every 5 seconds, to keep the link open.

The sent packet is not a RTP packet, but a STUN message including a CHANGE-REQUEST attribute with no-change flags. There's no need to have a STUN-aware server to use this RTP Keepalive mechanism. If a STUN server reads that message, its handling results into no actions, since it indicates there's no changes about the RTP stream.

Content of the dummy (but still valid) STUN packet:

  • STUN Message Type: Binding Request
  • Transaction ID: FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
  • CHANGE-REQUEST attribute:
    • No IP change
    • No Port change

Set this setting to off to switch this behavior off.

Valid Values

on, off

Default Value

on