As of today, Restcomm USSD Gateway implements 3GPP TS 24.390 (USSD for the IMS or USSI) for establishing, maintaining and releasing SIP transactions (with Content-Type: application/vnd.3gpp.ussd+xml) only with Restcomm-Connect (or any SIP AS that acts identically).
This is great and surely it's the only USSD Gateway out there with this feature. However, we need to fully implement USSD over SIP as per 3GPP TS 24.390, in order to being able to act as a stand-alone USSI-AS. This will become critical for USSD over LTE without Circuit-Switched Fallback. Furthermore, it has already been asked by customers.
Lets use version 13.2.0 of 3GPP TS 24.390 (released on 2016-09-30) as initial reference, as it introduces some critical enhancements/additions from its predecessors. Find it attached (Annex A contains very illustrative signalling flows and examples).
24390-d20.zip
As of today, Restcomm USSD Gateway implements 3GPP TS 24.390 (USSD for the IMS or USSI) for establishing, maintaining and releasing SIP transactions (with Content-Type: application/vnd.3gpp.ussd+xml) only with Restcomm-Connect (or any SIP AS that acts identically).
This is great and surely it's the only USSD Gateway out there with this feature. However, we need to fully implement USSD over SIP as per 3GPP TS 24.390, in order to being able to act as a stand-alone USSI-AS. This will become critical for USSD over LTE without Circuit-Switched Fallback. Furthermore, it has already been asked by customers.
Lets use version 13.2.0 of 3GPP TS 24.390 (released on 2016-09-30) as initial reference, as it introduces some critical enhancements/additions from its predecessors. Find it attached (Annex A contains very illustrative signalling flows and examples). 24390-d20.zip