To be become a LTE Expert?

• Proxy (P-CSCF ) - in a visited network
– When roaming, routes the SIP messages to the I-CSCF of the home network
– Allocates bearers and performs SIP header compression
• Interrogating (I-CSCF ) - border of home network
– Identifies the appropriate S-CSCF based on information from the HSS
• Serving (S-CSCF) - in the user’s home network
– SIP server for authentication and service establishment
– Provides access to Application server to the mobile