Question: What is one of the additional functions of the Serving GPRS Support Node (SGSN) in an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access, as described in 3GPP specifications?
Option 1: Handling of UE's IP address allocation
Option 2: Inter EPC node signalling for mobility between 2G/3G and E-UTRAN 3GPP access networks
Option 3: Selection of MME for handovers to UTRAN 3GPP access network
Option 4: Handling of UE's Quality of Service (QoS) parameters
Explanation: The SGSN plays a crucial role in handling mobility between different generations of networks, including 2G/3G and E-UTRAN. This function is essential for ensuring seamless handovers and maintaining session continuity as the UE moves across different access networks.