E2E active testing to ensure IMS quality across traditional and value-added offerings

IMS Testing

IP Multimedia Subsystem (IMS) is a key enabler for various services in today’s mobile networks, for traditional services such as voice in data-only and packet-based networks, and for new value-added services, designed to enhance the value proposition of mobile operators.

Mobileum offers a comprehensive set of tools that operators can use to test and periodically monitor their IMS services, in all stages of deployment, from lab to live operation. The suite of test cases covers all scenarios required to validate the IMS service and the interworking with other technologies. With full control of the IMS client (for wireless modules and S1 based tests) in-depth KPIs are provided, including SIP and RTP KPIs and the respective result files, e.g. PCAP traces, audio/video references, L3 Traces.

IMS Testing Use Cases

Due to the increase in over-the-top (OTT) applications, traditional voice services and revenues are declining. Furthermore, as the number of 2G and 3G networks decrease, IP Multimedia Services (IMS) have become an important solution for MNOs, as it allows them to diversify offerings, implement new pricing models, and partner or compete with OTT players. However, because of the complexity and interoperability with legacy technologies, IMS presents operators with new challenges, especially in roaming, when two networks and interconnecting parties are involved.

Mobileum’s IMS testing solution allows stack adaptation and automated periodic testing of the following use cases: 

❖ VoLTE testing via wireless modules, smartphones, or core network probes

❖ ViLTE testing on wireless modules

❖ VoWiFi testing via untrusted non-3GPP access, EAP-AKA authentication

❖ RCS testing using Mobileum’s RCSe client

❖ SMSoIP testing via wireless modules or core network probes

Mobileum’s IMS Testing Approaches

Typical IMS services require communication and coordination between several network nodes, in different areas of the operator’s network, RAN, EPC and IMS. Furthermore, the end-to-end service is established and delivered using different protocols, e.g SIP, RTP, HTTP, MSRP all running on top of IP.

Mobileum offers a comprehensive set of tools that operators can use to test and periodically monitor their IMS services, in all stage of deployment, from lab to live operation. The flexibility of the system allows different testing approaches: 

❖ LTE Wireless Interfaces and Mobileum's robust IMS client

❖ Core Network using S1 Core Network Probes and Mobileum IMS client for high volume testing, eliminating radio specific issues

❖ Real Devices using the native IMS client of the smartphone for QoE testing on commercial smartphones

The Mobileum IMS client

The Mobileum IMS Client performs end-to-end testing of IMS Services with full control over all layers of the IMS Stack and produces detailed KPIs down to the protocol level. The client can run over wireless modules (LTE Uu) or core network probes (S1) and test a wide range of IMS Services, e.g. VoLTE, ViLTE, VoWiFi, SMSoIP, RCS. It was developed according to GSMA IR.92, IR.94 profiles for Voice, SMS, and Video over LTE, IR.51 profile for Voice and SMS over WiFi and RCS Universal Profile, and the respective 3GPP standards.

Other features of the Mobileum IMS Client include: 

❖ Support for: P-CSCF discovery, IPv4, IPv6 or dual-stack IPv4v6, GBR/MBR dedicated bearers, and SIP over TCP or UDP

❖ Authentication over AKAv1-MD5, AKAv2-MD5 (or MD5) with IPSec support (3GPP TS 24.229, 3GPP TS 33.203)

❖ Support for alphanumeric, MSISDN and TEL URI addressing, and for media session negation over SIP-SDP

Voice over LTE (VoLTE) testing

VoLTE is an essential service for mobile operators, that enables voice support in LTE networks. It is fundamentally different and more complex, compared to traditional CS voice.

Mobileum’s VoLTE testing uses these approaches: 

❖ Wireless Modules (LTE Uu) for end-to-end testing, with full control of the IMS stack and the mobile, providing in-depth KPIs, Layer 3 (RRC and NAS) traces and various result files for troubleshooting and root-cause analysis.

❖ Core Network Interfaces (S1) to execute multiple test calls simultaneously and isolate faults by bypassing the RAN and eliminating radio-specific issues. In combination with LTE Uu interface using Wireless Modules, the operator can observe service QoS from two perspectives.

❖ On smartphones providing KPIs such as Call Setup Times or Voice Quality, measured directly form the device for insights on the user experience.

Are you getting the VoLTE customer experience and revenue you expected?

CSP’s are beginning to shut down 3G networks, with many now using LTE networks exclusively. This means voice calls are now using VoLTE, and the existing charging and revenue paradigm will have to change. VoLTE calls are not charged simply according to the time of call; instead, the call will be a data session that will consume a data bucket. Using Mobileum Test Factory, service providers can validate the roaming behavior of its customers on VoLTE networks so that business models can be confirmed or adapted as needed. Also, based on the roaming customer experience, service providers can determine the best suitable roaming agreements to provide a reliable VoLTE connection that meets the service provider standards.

VoLTE Test Cases

Mobileum’s wide range of VoLTE test cases cover all necessary scenarios for validating VoLTE services from an end-to-end perspective:

❖ Basic VoLTE – a set of test cases that can be used to check VoLTE call establishment, between two VoLTE subscribers or between a VoLTE subscriber and a 2G/3G/PSTN subscriber.

❖ VoLTE with Voice Quality – call establishment with additional voice quality measurements using the POLQA algorithm and multi-transmissions test cases to test the consistency of the MOS values, over the duration of the session.

❖ LTE Supplementary Services testing as defined in GSMA IR.92, e.g. Call Forwarding, Call Hold, Call Barring, Conference Call, Message Waiting Indication, and Voice Mail.

All VoLTE test cases can configure the testing scenario, e.g. IMS account and user password, P-CSCF address, URI type. Alternatively, the test cases support auto-configuration based on information stored in the USIM or ISIM.

To continuously test and monitor the availability and performance for VoLTE Services, and the interoperability with circuit switch voice, Mobileum recommends a minimum test setup that covers the following:

VoWiFi is one of the latest IMS-based services to be launched by mobile operators. It allows users to make voice calls using the data connection from any WiFi access point (untrusted non-3GPP access). The access technology, which is not controlled by the operator, adds another layer of complexity in providing adequate quality of service. Mobileum's VoWiFi testing solution allows operator to verify and periodically monitor the quality of the service. Our approach uses wireless modules as a flexible and robust solution for end-to-end VoWiFi measurements. It allows untrusted non-3GPP access and supports standard methods for WLAN authentication, e.g. WPA2 PSK. It uses EAP-AKA authentication for the IPSec tunnel between UE and ePDG.