Paging procedure signalling is divided into following two steps:
1. Paging message between MME and eNodeB.
2. Paging message between eNodeB and UE.
If UE was registered with MME for EPS and non-EPS services simultaneously then MME can page that UE for both types of services i.e. "circuit switch" as well as "packet switch". In case of incoming voice call, MME receives "SGsAP-PAGING-REQUEST" message from VLR, prepare and sends S1-AP Paging message to eNodeB with enable cs-indicator in CN domain IE of S1-AP Paging message. Similarly, when MME receives downlink data notification from SGW, it sends S1-AP paging message to UE with enable ps-indicator in CN domain IE of S1-AP message.