R&D Worldwide

IETF Working Groups

There are several IETF workgroups related to the IP-telephony area.

IP-Telephony

• avt (Audio/Video Transport): the group' task is specification of protocols for real-time transmission of audio and video over UDP and IP multicast
• sip (Session Initiation Protocol): The Session Initiation Protocol (SIP) working group is chartered to continue the development of SIP, currently specified as proposed standard RFC 2543. (See also the supplementary webpage .
• sipping has been chartered to investigate new signaling issues beyond core SIP specification. It's a kind of filter put in front of the SIP WG. (See also the supplementary webpage .
• iptel (IP Telephony): the primary purpose of the group is to develop supporting tools and signaling protocols for the IPT (e.g., TRIP and CPL)
• mmusic (Multiparty Multimedia Session Control): the group's task is development of protocols to support Internet teleconferencing sessions.

Interworking with Legacy

• pint (PSTN and Internet internetworking): the primary workgroup's goal is to bring PSTN services to Internet users; the proposed services are Click-to-{dial|fax}[-back] (e.g. click on a yellow-pages web-page to be contacted by a sales representative over PSTN), voice access to Web content.
• spirits (Service in the PSTN/IN Requesting InTernet Service): The WG addresses how services supported by IP network entities can be started from IN (Intelligent Network) requests, as well as the protocol arrangements through which PSTN (Public Switched Telephone Network) can request actions to be carried out in the IP network in response to events (IN Triggers) occurring within the PSTN/IN.
• enum (Telephone Number Mapping ): This working group will define a DNS-based architecture and protocols for mapping a telephone number to a set of attributes (e.g. URLs) which can be used to contact a resource associated with that number.
•  sigtran  (signaling transport): The primary purpose of this working group will be to address the transport of packet-based PSTN signaling over IP Networks, taking into account functional and performance requirements of the PSTN signaling. For interworking with PSTN, IP networks will need to transport signaling such as Q.931 or SS7 ISUP messages between IP nodes such as a Signaling Gateway and Media Gateway Controller or Media Gateway.
• megaco (Media Gateway Control): The WG develops an architecture and requirements for controlling PSTN Media Gateways from external control elements.

QoS

• diffserv (Differentiated Services): the workgroups's task is to experiment with methods of providing differentiated classes of service for Internet traffic
• intserv (Integrated Services): the purpose of this working group is to expand the Internet service model for the transport of audio, video, real-time, and classical data traffic within a single network infrastructure
• rsvp (Resource Reservation Setup Protocol): this workgroup develops and experiments with the Resource Reservation Setup Protocol
• mpls (Multiprotocol Label Switching ): the workgroup's scope is to develop a standardized label-swapped based forwarding technology ("label switching")

Miscellaneous

• midcom deals with problems related to traversal of boxes such as firewalls and NATs.
• simple generates guidelines for building instant messaging and presence services on top of SIP infrastructure.
• geopriv looks at various aspects of services depending on geographical location. Main concern is privacy and security issues.

Research Topics

• Transport and QoS Issues (RTP Scaling, Packet Loss Concealment, FEC, bandwidth reservation and admission control, synchronization with call signaling, bandwidth adaption, codec optimization)
• Service Creation (applications, languages, provisioning, feature interaction)
• Operational Issues (network dimensioning, provisioning, interdomain aspects)
• Mobility (efficient routing, hand-offs, mobility layering)
• Security Aspects