Description: Lync Customer gets disconnect while trying to park or hold

Why: The mediation server is configured to use RTCP. After the gateway receives a=sendonly or a=inactive in the SDP, it doesn’t send any media traffic (no RTCP). The server ends the connection with RTCP timer is not disabled and Mediation Server encountered a gateway media stream timeout.

Resolution:

Set the mediation server setting with this switch to disable RTCPActiveCalls and RTCPCallsOnHold: Set-CsTrunkConfiguration -RTCPActiveCalls $false -RTCPCallsOnHold $false -EnableSessionTimer $True

More Info

RTCPActiveCalls

This parameter determines whether RTCP packets are sent from the PSTN gateway, IP-PBX, or SBC at the service provider for active calls. An active call in this context is a call where media is allowed to flow in at least one direction. If RTCPActiveCalls is set to True, the Mediation Server or Lync Server client can terminate a call if it does not receive RTCP packets for a period exceeding 30 seconds. Note that disabling the checks for received RTCP media for active calls in Lync Server elements removes an important safeguard for detecting a dropped peer and should be done only if necessary. The default is True.

RTCPCallsOnHold

This parameter determines whether RTCP packets continue to be sent across the trunk for calls that have been placed on hold and no media packets are expected to flow in either direction. If Music on Hold is enabled at either the Lync Server client or the trunk, the call will be considered to be active and this property will be ignored. In these circumstances use the RTCPActiveCalls parameter. Note that disabling the checks for received RTCP media for active calls in Lync Server elements removes an important safeguard for detecting a dropped peer and should be done only if necessary. The default is True.

EnableSessionTimer

This parameter specifies whether the session timer is enabled. Session timers are used to determine whether a particular session is still active. Note that even if this parameter is set to False, session timers can be applicable if the remote connection has session timer enabled. In such a case, the Mediation Server will reply to session timer probes from the remote entity. The default is False.