Bringing Voice and SMS Revenues to LTE
As operators begin planning their LTE deployments in earnest, one critical challenge quickly comes to the forefront; how to deliver their existing voice and SMS services over this new packet-based access network.
When LTE standardization began a number of years ago, it was assumed that operators would have transitioned their core voice networks over to IMS-based systems by the time LTE deployment began. As a result, only an IMS-based approach was specified within 3GPP for delivering voice and SMS service over LTE.
While the ultimate plan of record remains IMS-based telephony for all operators, for many, the timing for their transition to IMS telephony is well beyond the timing of their LTE deployments. As a result, these operators are left without a means to bring their primary revenue-generating voice and SMS services to their new LTE networks.
To address this gap, a number of major players in the mobile industry started an initiative called VoLGA, or Voice over LTE via the existing 3GPP GAN standard, and created the VoLGA Forum.
The concept of VoLGA is to ‘elevate’ an operator's existing voice and SMS core service network to act as a packet service over LTE. As a result, operators can immediately bring all of their existing voice and SMS services to their LTE networks without requiring any changes to their existing core service network.
For operators not prepared to make the transition to IMS-based voice in the near to mid-term, the alternative to VoLGA is an approach known as CS Fallback, or CSFB. With CSFB, handsets 'fall back' from the LTE network to a 2G or 3G network whenever they need to use a voice or SMS service. VoLGA has a number of key advantages over CSFB, including:
- Superior end-user experience VoLGA provides the same or better user experience for voice services over LTE than users receive over current 2G or 3G networks. For example, call setup times with VoLGA can be significantly faster than with today's 2G/3G networks, while with CSFB, call setup times can be significantly longer.
- Low operational cost/complexity Unlike CSFB, VoLGA does not require any modification or upgrade to an operator's existing core service network.
- A path to IMS Also unlike CSFB, VoLGA fully supports an operator's evolution to IMS-based services. For example, VoLGA supports IMS Rich Communications Suite (RCS), where voice and IMS data are delivered as combinational services over LTE.
VoLGA is the most pragmatic approach for voice over LTE today and provides a smooth migration to IMS telephony. For more information, please visit VoLGA-Forum.com.
