Until voice over LTE (VoLTE) services become available, carriers are supporting voice and SMS for the new crop of 4G LTE smartphones, such as iPhone 5, by using their legacy 3G core infrastructure. One disadvantage, according to Mavenir Systems, is that two radios may be active on the handset -- one for LTE and one for the legacy 3G -- in order to handle the voice and SMS signalling and traffic.
Mavenir proposes a Circuit Switch Fallback (CSFB) solution that overlays the legacy infrastructure that enables delivery of circuit-switched voice services to LTE handsets by triggering "fall back" to the 3G network to complete voice calls. With CSFB, operators can immediately support new LTE-enabled smartphones, such as the newly announced iPhone 5, for voice and SMS in advance of IMS-based VoLTE solutions that won’t be widely available until 2014. This overlay approach does not impact the MSC core and means that the operator will not have to invest more in its legacy
“Our value proposition is combining proven CSFB technology with our speed to market and the ease of integrating into 4G LTE networks.” said Pardeep Kohli, president and chief executive officer of Mavenir Systems. “Our IWF CSFB function helps the network economics of introducing new LTE services quickly and cost effectively. This is the first step for many operators, but they can easily leverage this Mavenir CSFB investment along the path to SRVCC and VoLTE.”