SIP Call Hold

This feature allows the IMG to process a re-INVITE from a SIP endpoint that places a call on hold or releases a hold. This addition complements the support for SIP Hold ( via 0.0.0.0 ip address) by supporting RFC 3398 section 9, allowing for the proper Interworking of hold information between SIP and SS7.

 

RFC

RFC 3398 Integrated Services Digital Network (ISDN) User Part (ISUP) to Session Initiation Protocol (SIP) Mapping: section 9

 

Call Flows

Suspend then Resume from SS7 side

Upon receiving a SUS message from the remote SS7 side, the IMG sends a re-Invite to the remote SIP side with the Connection IP address set to 0.0.0.0 in order to request that gateway to place the call on hold.

 

 

CF_SIP-Hold_From_SS7.png

 

 

 

Suspend then Resume from SIP side

Upon receiving a re-Invite with the connection address equal to a valid IP address for a call that has been placed on hold, the IMG sends a CPG message with the notification indicator set to ‘remote hold released’ to the remote SS7 ANSI side.

 

 

CF_SIP-Hold_From_SIP.png

 

 

 

Suspend then Resume from SS7 side when SIP-T is enabled

When SIP-T is enabled, the IMG will encapsulate the RES message received into an Info message instead of sending a Re-invite to the SIP side.

CF_SIP-Hold_SIP-T.png