- Even today, Release 4 is still synonymous with the definition of the Bearer Independent Core Network (BICN) or, in other words, the virtualization of the circuit switched network.
- Introduction of the IMS which has continued to be developed throughout all following releases
- The specification of High Speed Downlink Packet Access (HSDPA). I think this is one of the single most important features ever specified. Without it, UMTS would look entirely different today.
- Introduction of High Speed Packet Uplink (HSUPA)
- Specification of HSPA+ with 64QAM and MIMO
- Enhancements to conserve battery power and to make state changes quicker for a better browsing experience. Also referred to as Continued Packet Connectivity
- HSUPA 16QAM for a faster uplink
- Extended Cell Range. Wasn't that done for Australia?
- The LTE baseline release
- Definition of Dual Carrier HSDPA
- Simultaneous use of 64QAM and MIMO on a single carrier
- Single Radio Voice Call Continuity to hand-over voice calls from a packet to a circuit switched bearer
- Femtocell definition (Home NodeBs)
- Small but Important: ICE (In Case of Emergency) information storage on the SIM card and retrieval in a standardized way to help first responders to contact your family and friends in case something has happened to you.
- Separate dual carriers to simultaneously transmit downlink data in the 900 and 2100 MHz band.
- Dual carrier in the uplink
- Inclusion of the European Digital Dividend band
- Information on the content of Release 10 is still sketchy at this time. The one thing that is clear at this point that it will contain the baseline for LTE Advanced.