Cisco ASR 5x00 Administration Manual page 296

▀ Rel. 7 Gx Interface
Figure 28.
Table 23.
Step Description
1 UE (IMS subscriber) requests for primary PDP context activation/creation.
2 SessMgr allocates an IP address to the UE.
3 SessMgr requests IMS Authorization, if IMSA is enabled for the APN.
4 IMSA allocates resources for the IP CAN session and the bearer, and selects the PCRF to contact based on the user's
selection key (for example, msisdn).
5 IMSA requests the DPCA module to issue an auth request to the PCRF.
▄ Cisco ASR 5x00 Packet Data Network Gateway Administration Guide
296
Rel. 7 Gx IMS Authorization Call Flow
Rel. 7 Gx IMS Authorization Call flow Description
Gx Interface Support