Products
Learn More
LTE operators are looking at various options to preserve vital Voice and Messaging revenues on their networks as a range of LTE enabled mobile devices are launched. The industry has agreed on two architectural approaches to support this objective, each offering a business value based on the operators' LTE coverage strategy. Circuit Switch Fall Back (CSFB) advocates the use of existing circuit switch (CS) core infrastructure for voice & SMS services, and a 3GPP defined IMS-based solution, endorsed by GSMA Voice and SMS over LTE (VoLTE) initiative, is seen as a target solution for providing multimedia services in LTE networks.
The deployment of LTE infrastructure already puts significant increased pressure on operator budgets. Any unnecessary investment in the legacy CS core, mandated by both approaches, reduces the speed with which an operator can deploy the new technologies, thus putting them at a competitive disadvantage.
Mavenir created the VoLTE Interworking Function (IWF) solution specifically to provide an alternative means of supporting new technologies to remove the risk, cost and time to market disadvantages associated with legacy core network upgrades. With Mavenir's CSFB IWF, LTE operators can preserve lucrative voice and SMS revenues, assure global roaming and interoperability, and get to market rapidly to compete against traditional and new OTT players.
VoLTE IWF for CSFB (CSFB IWF)
The intent of CSFB is to minimize back office integration time, reduce network cost/complexity and re-use interconnect/ roaming agreements and charging / settlement processes available in the CS voice core. However, LTE operators deploying CSFB are faced with re-investment in the legacy core due to mandatory changes required to the MSC & SGSN and some inevitable replacement of legacy MSC. CSFB requires significant re-engineering and ongoing process changes.
Mavenir's VoLTE IWF facilitates the rapid deployment of LTE with CSFB by eliminating the need for MSC upgrades and reducing operational complexities in deploying LTE voice and SMS services. Investment made for the CSFB IWF is based on a common platform for future evolution to converged voice and messaging applications including IMS-based VoLTE. This investment is strategic, rather than the tactical approach required by incumbent MSC vendors.
The VoLTE IWF for CSFB is a centralized solution with standard interfaces. It supports the SGs interface from the MME in the EPC domain. It interacts with the HLR over MAP for location management, subscriber management and call handling procedures. The MAP interface between CSFB IWF and SMSC is used for mobile originated and mobile terminated SMS.
VoLTE IWF for SR-VCC (SR-VCC IWF)
The deployment of IMS-based VoLTE solution introduces a new set of requirements on the legacy CS core for the purpose of mobility. The need for call survivability across LTE and 2G/3G networks, when the user roams out of LTE coverage, is enabled by SR-VCC (Single Radio VCC), defined in 3GPP Release 9 and is further enhanced in Releases 10 & 11. This again mandates an additional upgrade to the MSC with a new Sv interface.
In line with the tradition of introducing standards based, cost effective solutions for VoLTE that allow time to market advantages to service providers, Mavenir introduces an Inter working function enabling SR-VCC in LTE networks that doesn’t require time and money consuming upgrades to legacy MSCs. The solution introduces SR-VCC IWF bridging CS core and EPC core by front ending the legacy MSCs in the operator network. The solution is agnostic of actual transfer of user sessions being controlled by SCC-AS or by ATCF in the network. The SRVCC IWF is a pure signaling solution reusing existing bearer capabilities of the network.
The CSFB IWF and SRVCC IWF share the same hardware and software platform, deployed on our carrier grade, ATCA-based, Mavenir mOne™ Convergence Platform. An operator who is looking for CSFB as interim solution and SRVCC as final solution for VoLTE, can deploy CSFB IWF to start with and later perform a software upgrade to enable SRVCC IWF functionality, avoiding the need for any MSC upgrades for CSFB (SGs) or SRVCC (Sv).
