Frequently Asked Questions

  1. What is IMS?
  2. What is the purpose of IMS?
  3. What is IMS AG?
  4. What standards does IMS AG test?
  5. What is the relationship of IMS AG to standardization bodies?
  6. Why do my company’s products / services need to be interoperable with other vendors?
  7. Should my company participate in the IMS AG?
  8. How can my company join the IMS AG?
  9. What responsibilities do members have?
  10. What are the benefits of the IMS AG to the mobile industry?

Q.  What is IMS?

A.  IMS stands for IP Multimedia Subsystem. It is a standardized Next Generation Networking (NGN) architecture, adopted by telecom operators – both mobile and fixed, for providing multimedia services. It uses a Voice-over-IP (VoIP) implementation based on a 3GPP standardized implementation of SIP, and runs over the standard Internet Protocol. Existing phone systems, both packet-switched and circuit-switched, are supported by IMS.

Q.  What is the purpose of IMS?

A.  The aim of IMS is to provide new services as well as all current and future services the internet provides. IMS gives network operators and service providers the ability to control and charge for individual services. Users will be able to execute all their services when roaming as well as from their home networks. To achieve these goals, IMS uses open standard IP protocols, defined by several standardization organizations.

Q.  What is IMS AG?

A.  The IMS AG is an IMTC Activity Group, which deals with the testing of interoperability of IMS clients. As this work is large and far reaching, the IMS AG is currently focusing on CSI and VS services:

  • CSI deals with combining circuit switched and IM sessions simultaneously between the same two users.
  • VS deals with video sharing services, where users can send live video pictures to someone and talk to them at the same time.

Additional services will be approached and dealt with in this activity group, according to the member company’s interests and market needs.

Q.  What standards does IMS AG test?

A.  At the moment, these are IETF and 3GPP standards, from the point of view of the actual service and not only from a protocol perspective. As the amount of services dealt with by the activity group will grow, so will the standards being tested.

  • GSMA VoLTE upcoming specification (based on One Voice work)
  • 3GPP TS 24.279: “Combining Circuit Switched (CS) and IP Multimedia Subsystem (IMS) services”
  • GSMA IR.74: “Video Share Interoperability Specification 1.0″

Q.  What is the relationship of IMS AG to standardization bodies?

A.  The IMS AG is a subgroup of IMTC, an industry consortium dedicated to promoting multimedia communication standards. IMTC is focused on interoperability. It is important to note that IMS AG and IMTC are not standards bodies. However, IMTC and its subgroups can interact with standards bodies through liaison relationships and through the actions of individual member companies.

A liaison relationship is an official channel of communication with another body. These relationships allow the IMS AG to make official contributions to the relevant working group meetings of these organizations, and improves communication between the organizations. Liaison statements and other documents resulting from these communications may be found here.

Q.  Why do my company’s products / services need to be interoperable with other vendors?

A.  IMS uses open standards in order to provide a wide range of services. To deploy an IMS network successfully, many vendors must participate to make this happen. Terminals, in particular, must interact with components not only in the user’s home network, but also in other networks while roaming. For this reason, content, servers and terminals from different vendors must work seamlessly together.

Q.  Should my company participate in the IMS AG?

A.  If your company is developing an IMS client, or if your products are interacting extensively with IMS clients, participation in the IMS AG will be beneficial to your company.

Q.  How can my company join the IMS AG?

A.  For information on how to join, please contact Tsahi Levent-Levi, IMS AG co-chairs at .

Q.  What responsibilities do members have?

A.  The main responsibility is to actively participate in planning and execution of the interoperability tests. IMS AG members also attend a weekly conference call for test planning, status updates, and improvement of the procedures. Testing will occasionally involve travel to live test events such as the IMTC SuperOp!

IMS AG members are also responsible for protecting the confidentiality of other members. Details may be found in the IMTC Rules of Engagement.

Q.  What are the benefits of the IMS AG to the mobile industry?

A.  The IMS AG provides a place where IMS client solution vendors may test their implementations in an open, accessible environment. The product interoperability, which results from these tests, is necessary to enable and expand the market for wireless and wire line multimedia products based on the IMS standards. Knowledge gained through testing in the IMS AG is actively fed back into the standardization process to clarify and improve the relevant specifications.