Section: Resume Acknowledge
Content: The Resume Acknowledge message should be sent on the S11 interface by the SGW to the MME and on the S5/S8 by the PGW to the SGW as part of the resume procedure returning back to E-UTRAN in the case of CS fallback or SRVCC. The Resume Acknowledge message should also be sent on the S4 interface by the SGW to the SGSN and on the S5/S8 interface by the PGW to the SGW as part of the resume procedure returning from SRVCC to HSPA if there is no Modify Bearer Request message sent to the SGW and PGW as specified in 3GPP TS 23.216[ Single Radio Voice Call Continuity (SRVCC); Stage 2 ]  [43]. The PGW shall also send a Resume Acknowledge message to the SGW on the S5/S8 interface as a response to a Resume Notification message sent by the SGW upon receipt from the MME/S4-SGSN of a (non-empty) Modify Bearer Request used as an implicit resume of the suspended bearers in the SGW and in the PGW (see 3GPP TS 23.216[ Single Radio Voice Call Continuity (SRVCC); Stage 2 ]  [43] clauses 6.2.2.1 and 6.3.2.1, 3GPP TS 23.272[ Circuit Switched (CS) fallback in Evolved Packet System (EPS); Stage 2 ]  [21] clauses 6.3, 6.5 and 7.4) if the conditions of presence of the IEs in the Modify Bearer Request specified in table 7.2.7-1 do not require any IE to be sent to the PGW. Possible Cause values are specified in Table 8.4-1. Table 7.4.4-1 specifies the presence requirements and conditions of the IEs in the message. Table -1: Information Element in Resume Acknowledge