Can you please advise if existing ims implementation supports integration with ims AS (Application Server), in particular for the third party registration:

- upon UE registration is completed, S-CSCF constructs Register message (which keeps all details of subscriber register message) and submits it to AS server as regular SIP-message (TS 24.229 5.4.1.7 Notification of Application Servers about registration status). S-CSCF obtains AS address from SAA (Server Assignment Answer) diameter message, received from HSS upon successful registration.