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VoLTE and SRVCC Test Solution

VoLTE and SRVCC Test Solution

Easy-to-use, high-performance and high-capacity load testing solution to enable IMS device and network testing during the various stages of VoLTE and eSRVCC development and deployment.


  • 10 million VoLTE endpoints
  • 5 million IPSec and TLS sessions
  • 1.28 M RTP/SRTP and RTCP/SRTCP streams
  • Real-time quality of service (QoS) metrics for all streams
  • Voice, video and data QoS metrics
  • Distributed-denial-of-service (DDOS) attacks and theft-ofservice
  • (ToS) tests
  • Media pinhole opening and closing tests
  • Policy-and-charging-function (PCRF) emulation
  • Home subscriber server (HSS) emulation
  • Enhanced MSC emulation for SRVCC and eSRVCC tests
  • IMS (CSCF) core network emulation
  • Mix of VoIP, VoLTE, RCS and WebRTC service tests


The mobile world is steadily but inescapably shifting to LTE. Voice remains a half-a-trillion-dollar business which is embracing Voice over LTE, or VoLTE. Furthermore, web real-time communication (WebRTC) and rich communication services (RCS) are required to protect declining revenues for mobile network operators as a result of free over-the-top (OTT) services. These services are hosted and delivered by IP multimedia subsystem (IMS) infrastructure (devices and network) to end users across different IP connectivity (IP-CAN) access networks.


VoLTE is a GSMA profile of the standards definition for the delivery of services currently provided via circuit switch networks–mainly voice and SMS–over the packet-switched only network of LTE, leveraging the core network IMS. Single radio voice call continuity (SRVCC) provides seamless voice call continuity when an UE handovers from LTE to 2G/3G access networks. Enhanced SRVCC (eSRVCC) introduces support for advanced features such as mid-call and alerting. It also introduces access transfer control function (ATCF) and an access transfer gateway (ATGW) that anchors the media in IMS network to drastically reduces handover setup time from more than 1 second to less than 300 milliseconds. The ATCF function is implemented in P-CSCF and SBC devices and the ATGW function is implemented in IMS-MGW and SBC.


The experience gained over years from various VoLTE trails and deployments have proven the intricate complexity of this whole environment and have shown how challenging reaping the benefits of the IMS promise can be. The high costs and delays all too often incurred are invariably linked to the high number of failures taking place in the field, as well as interworking failures between different devices in the IMS network, particularly during high busy-hour call attempts (BHCA). These failures however, could be nipped in the bud, since they can be detected and corrected in the lab.

EXFO’s QualityAssurer is an IMS load-testing simulator used in labs to verify whether the IMS network and devices are delivering the expected VoLTE and eSRVCC performance prior to deployment. The QualityAssurer is ready to go and comes with a comprehensive set of advanced high-capacity and high-performance load-testing capabilities. With the help of its easy-to-use features, the QualityAssurer helps ensure the timely identification of failures. This enables operators to deploy the IMS network, devices and services such as VoLTE in live networks with the highest levels of service quality and customer satisfaction, and faster time to market.

The EXFO QualityAssurer supports the characterization of performance of the IMS network and devices such as A-SBC, I-SBC, E-SBC, P-CSCF, I-CSCF, S-CSCF, MGW, SCC-AS, TAS, HSS, DRA, PCRF and more.The top five VoLTE test configurations are explained below:

  1. Test session border controller (SBC) VoLTE functions by emulating VoLTE subscribers, policy charging and rules function (PCRF), call session control function (I-CSCF and S-CSCF) and home subscriber server (HSS).
  2. Test call session control function (P-CSCF, I-CSCF and S-CSCF) VoLTE functions by emulating VoLTE subscribers, policy charging and rules function (PCRF) and home subscriber server (HSS).
  3. Test end-to-end IMS core (SBC, I-CSCF, S-CSCF, HSS, SCC-AS and TAS) VoLTE, SRVCC and eSRVCC functions by emulating VoLTE subscribers, enhanced 2G/3G MSC (e-MSC) and policy charging and rules function (PCRF).
  4. Test session border controller (SBC), call session control function (I-CSCF and S-CSCF) and session call continuity application server (SCC-AS) VoLTE, SRVCC and eSRVCC functions by emulating VoLTE subscribers, policy charging and rules function (PCRF), enhanced 2G/3G MSC (e-MSC) and home subscriber server (HSS).
  5. Test IMS media gateway (IMS-MGW) VoLTE, SRVCC and eSRVCC functions by emulating VoLTE subscribers, enhanced 2G/3G MSC (e-MSC) and media gateway controller (MGC).


  • Simulates millions of VoLTE subscribers to test IMS network or devices, hence enabling selection of the right network devices for VoLTE service deployment
  • Tests signaling performance and capacity such as registration throughput, registration capacity, call session establishment rate and call session capacity
  • Tests media performance and capacity e.g., whether concurrent media sessions IMS network and devices are able to set up and maintain, with and without transcoding
  • Verifi es the impact on VoLTE service performance as a result of resource-intensive functions such as signaling security interworking (TLS to/from IPSec) and media security interworking (RTP/RTCP to/from SRTP/SRTCP)
  • Generates and analyses line-rate (1G and 10G) voice and video streams for delay, jitter, packet loss and mean opinion score (MOS)
  • Checks whether the IMS networks and devices are able to deliver the expected QoS with various quality parameter settings, such as ToS/ differentiated services code point (DSCP), VLAN and MPLS
  • Benchmarks the performance of handover functionality of access transfer control function (ATCF) and access control gateway function (ATGW) and session call continuity application server (SCC-AS) devices Tests SRVCC and enhanced eSRVCC PS to CS call features from basic call to alerting to mid-call (2 or 3 UE) features
  • Performs high-availability tests to determine how resilently the IMS network operates under overload conditions, security attacks (DDOS, rogue media), card and port failover scenarios
  • Tests that the IMS network is able to linearly scale to accommodate growing loads without any performance/capacity degradation
  • Exercise the entire operator IMS network infrastructure, physical and network functions virtualization (NFV), by testing end-to-end service delivery with the mix of business VoIP,VoLTE, RCS/MSRP and WebRTC services