The VoLGA Forum has announced a set of new features for delivering mobile voice and SMS services over LTE. New features included are:

• support for SIM-less emergency calling
• optimized voice-bearer routing
• host APIs for LTE handsets

In addition to above VoLGA has extended its architecture to support 3G/HSPA in phase 2 specifications. New specifications now support Voice (and other CS services) over LTE via Generic Access (VoLGA) and "VoLGA" service over UTRAN packet access. 

Addition of 3G via VoLGA is surprising however it gives another option to provide  seemless voice service via existing 3G packet switched networks. With this enhancement now voice calls can be placed via 3G packet network using VoLGA and handover to CS is also possible. With VoLGA over UTRAN packet access, following new options are possible for voice calls.

• handover from E-UTRAN to a UTRAN PS domain (Voice Call remains VOIP)
• handover from UTRAN PS to a GERAN or non-VoIP capable UTRAN target cell (Voice Call switches from PS voice to CS Voice)

See below the roaming architecture in UTRAN PS case, for E-UTRAN refer VoLGA wiki.

It would be interesting to know why VoLGA Forum has extended VoLGA services to 3G, as of now it just gives another option for operators to use VoLGA for 3G PS as well. Concept is similar to UMA/GAN, radio access network has been replaced from WiFi to 3G UTRAN. 

Just to mention VoLGA does not support CS to PS handover from GERAN/UTRAN CS domain to E-UTRAN or UTRAN PS.