After placing a PSAP call a subscriber may receive a return call from the PSAP (for example to confirm the subscriber’s physical location). PSAP callbacks must not be blocked or delayed by MMTel features. The two features here are responsible for identifying appropriate calls as PSAP callbacks and (if required) recording that a PSAP call has occurred.

Feature What it does

determines whether a received SIP INVITE corresponds to a PSAP callback, and stops any other features that could potentially prevent the call being set up.

identifies SIP MESSAGES sent to the AS by E-CSCF to notify the AS that a subscriber has placed an emergency call. The feature records this information in Cassandra where it can be used by MMTel Determine PSAP Callback to identify calls as potential PSAP callbacks.

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Sentinel VoLTE Version 3.0.0