What is VoLGA? Mobile operators evaluating Long Term Evolution (LTE), the next-generation, all-IP mobile access network, realize they must support voice and SMS services from the beginning. While IMS telephony is the plan of record for many operators, there is a growing realization that an IMS investment is outside the LTE planning horizon. There is a need to provide voice and SMS services over LTE today.

VoLGA is a technology approach for mobile operators to deliver voice and SMS over LTE today.

What about CS Fallback to provide voice and SMS services today? CS Fallback (CSFB) was defined in 3GPP as an interim step to overcoming the voice over LTE problem. Unfortunately, CSFB provides a sub-standard user experience, as well as being costly and non-trivial to implement.

The concept of CS Fallback is to force the user/handset to drop an LTE connection and fall back to a 2G or 3G network to place or receive calls. The process of falling back adds substantial delays to call connect times and may incur additional call drops during network handovers.

To support CSFB, operators must upgrade their MSC network, a costly and time-consuming process for an 'interim' solution.

But perhaps most disappointing is that CSFB is not actually voice over LTE. It's voice over 2G/3G networks. For an operator, this is painfully counter-intuitive. LTE is the most cost-effective, highest performance network, yet the operator's most valuable services (Voice and SMS) are not supported. For more information on the short-comings of CSFB, check out this whitepaper.

A native voice over LTE solution like VoLGA is by far the most pragmatic solution available.