If I understood your problem correctly.
UE can send attach request to MME with the following possible modes:
1. PS Mode1: when UE wants to get attach with network for EPS services only and UE usage setting is "voice centric"
2. PS Mode2: when UE wants to get attach with network for EPS service only and UE usage setting is "data centric".
3. CS/PS Mode 1: UE registers with network for EPS and non-EPS services and UE usage setting is "voice centric".
4. CS/PS Mode 2: UE registers with network for EPS and non-EPS services and UE usage setting is "data centric".
