Question

Why in 4G the EPC session is considered as "always on", what does it mean and how is it different with 2G & 3G?

Answer 1

Though I don't know how 2G and 3G technology work but in LTE "always-on" means an IP addressed is allocated to the UE and it keeps that IP until it gets detached from the network. Even if there is no data flow for UE, it still retains the allocated IP address as well as PGW retains UE's IP address.

hope that help you.....