The SIP Media Inactivity Timer feature enables Obi gateways to monitor and disconnect Voice-over-IP (VoIP) calls if no Real-Time Control Protocol (RTCP) packets are received within a configurable time period.
When RTCP reports are not received by a the gateway, the SIP Media Inactivity Timer feature releases the hung session and its network resources in an orderly manner. These network resources include the gateway digital signal processor (DSP) and time-division multiplexing (TDM) channel resources that are utilized by the hung sessions. Because call signaling is sent to tear down the call, any stateful SIP proxies involved in the call are also notified to clear the state that they have associated with the hung session. The call is also cleared back through the TDM port so that any attached TDM switching equipment also clears its resources.
You need to log into your Obi via Obitalk, choose your required ISTP (A,B,C or D) Profile - RTCP. Default is NOT enabled, uncheck and click on Enable. This should successfully tear down the call if a 603 error occurs within 10 seconds.