- Initiated by network to modify an EPS bearer context with specific QOS and TFT.
- It can also be initiated when UE sends bearer resource allocation request or bearer resource modification request.
- It can also be initiated by network to update APN of UE in case of inter system handover.
- MME will initiate this procedure by sending MODIFY EPS BEARER CONTEXT REQUEST to UE. MME also includes a EPS bearer identity to identify which EPS bearer Context to be modified.
- UE shall apply the received TFT for all uplink traffic to radio bearers if the modify request contains a TFT that has packet filters.
- If there are no Guaranteed Bit Rate or Maximum Bit Rate values for uplink or downlink in received modification request UE shall use previous received values.
- UE may reject the request with following causes
#41 Semantic errors in TFT
#43 Invalid EPS bearer Identity
Reference 3GPP TS 23.401