This feature analyses an incoming INVITE request to determine if it is a USSI request.

Feature cheat sheet

Feature Name Network Operator Data Used in PlanId(s) Stateful or Stateless POJO Feature or SBB Feature



All INVITE Sessions



Session Input variables


Session Output variables



DetermineUssiMode statistics are tracked by the sentinel.ipsmgw SBB and can be found under the following parameter set in REM:
SLEE-Usage → sentinel.ipsmgw service → sentinel.ipsmgw SBB → feature → DetermineUssiMode
or with rhino-stats:

Name Description

Incremented when the feature is started.


Incremented when Sentinel encounters an error while attempting to start the feature.


Incremented when a non-fatal problem is encountered and the feature and issues a warning.


Incremented when a fatal problem is encountered and the feature cannot execute correctly.


Incremented when the feature takes too long to complete and Sentinel aborts execution.


Incremented when it is determined that the incoming request is not a USSI request.


Incremented when it is determined that the incoming request is a USSI request.


On receiving an incoming SIP request, this feature checks the request against the following conditions:

  • The request method is INVITE.

  • The Request-URI is a SIP URI (i.e. the URI starts with sip:).

  • The Request-URI has a user parameter with the value set to dialstring.

  • The user part of the Request-URI is a valid USSD dial string according to 3GPP TS 22.090.

If all of the conditions are met, the feature will increment the MessageIsUssiRequest statistic and finish execution, allowing message processing to proceed.

If any of the conditions are not met, the feature will increment the MessageNotUssiRequest statistic, and instruct the SIP session to proxy the request without recording Sentinel on the route. The feature will then finish execution.

Previous page Next page
Sentinel IP-SM-GW Version 4.1