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FoIP Task Group Charter

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Task Group Co-Chairs: Gonzalo Salgueiro – (Cisco Systems); Max Schroeder — (Faxcore)
Task Group Whip: Max Schroeder — (Faxcore)
Allan Ashmore – (Dialogic)
Shaun Bharrat – (Sonus)
Sebastien Boire-Lavigne – (Sagem-Interstar)
Gerard Boulay – (Orange)
Eric Burger – (Georgetown University)
Michael Chen – (LSI)
Stephen Choy – (Cisco Systems)
Mike Coffee – (Commetrex)
Quentin J. Dible – (Faxback)
David Hanes – (Cisco Systems)
Steve Hersee – (Copia International)
Paul Jones – – (Packetizer)
Mike Oliszewski – (Faxback)
Alan Percy – (AudioCodes)
Marc Robins – (SIP Forum)
Gonzalo – (Cisco Systems)
Ed Shultz – (LSI)
Jerzy Soldrowski – (Telecom Poland)
Simon Yee – (Sagem-Interstar)
Meetings: Meetings take place on an ad-hoc basis. You can stay informed about upcoming meetings by subscribing to the foip email list (see link above).

FoIP Task Group Charter

The proposed charter of the SIP Forum FoIP task group is to investigate ongoing issues with the deployment of fax services, specifically ITU T.38, in SIP networks. SIP networks cannot adequately replace analog PSTN in enterprises unless essential services such as FAX are accommodated.

The use of ITU T.37 email based store and forward has not been successful due to the specific legal status fax enjoys in law and that fax communications has 3rd party confirmation of transmission and/or delivery in carrier billing records (non repudiation). Classic FAX (T.30) over G.711 has not proved to be reliable and SIP communications , in the future, may use other codecs that have been proven to break T.30 such as G.729 and other high compression codecs like SPEEDEX etc.

The SIP Forum FoIP task group is chartered to accomplish the following tasks:

  1. Fully document what the current issues are surrounding ITU T.38 in SIP networks.
    • a. What interoperability testing procedures currently exist.
    • b. What are the common factors in T.38 failure such as page length or lack of ECM support in carrier gateways and ATA’s.
    • c. Network packet loss considerations.
  2. Determine what solutions are currently available to address the problem.
  3. Determine if the problem can be solved within the scope of existing IETF SIP and ITU T.38 Recommendations.
  4. If the problems can be solved using existing standards by tightening requirements, document the procedures vendors and carriers need to implement in an appropriate SIP Forum Technical Recommendation.
  5. If, in the judgment of the SIP Forum FoIP WG, existing IETF and or ITU standards need to be modified, develop a strongly worded recommendation to the appropriate Standards Development Organization (SDO) on what the SIP Forum FoIP WG has discovered and recommend appropriate action by the SDO to remedy the issue.

Participation in the Task Group

The board of directors of the SIP Forum has appointed Neil Weldon, Dialogic Corporation, as chair for this task group to
coordinate the creation of the various activities of the group. The various activities are intended to be open to all members—full, academic and participant—as determined by the Task Groups and the Working Group Chair.

The Task Group is currently meeting via teleconference on a weekly basis. The group has completed a comprehensive Problem Statement that describes the various issues that are currently impacting the reliability of Fax-over-IP transmission. View this document in the FoIP Task Group document repository.


The FoIP Task Group will establish various activities as required to support its activities. The specific meeting and operational schedule for each activity will be established by the chair.

FoIP Task Group Activities

In May 2013, the FoIP Task Group has achieved a significant milestone in its mission to improve international IP fax transport services with the publication of RFC 6913 – a new Internet Engineering Task Force (IETF) RFC that introduces a new “sip.fax” media feature tag that aims to enable the intelligent routing of International faxes and greatly improve the reliability of International faxing services.

RFC 6913, co-authored by David Hanes, Kevin Fleming and Gonzalo Salgueiro, defines and registers with IANA a new “fax” media feature tag for use with the Session Initiation Protocol (SIP). Currently, fax calls are indistinguishable from voice calls at call initiation. Consequently, fax calls can be routed to SIP user agents that are not fax capable. A “fax” media feature tag implemented in conjunction with caller preferences allows for early advertisement of fax capabilities and consequently, more intelligent fax call routing.

See the full text of the RFC 6913 announcement.

In June 2010, the SIP and i3 Forums joined forces with the common purpose of making FoIP viable in international calls. The FoIP Task Group of each organization was assigned to perform the necessary testing, analysis, and remediation to allow the global telecom network to make the transition to an all-IP transport, and do so with robust FoIP.

The two groups decided to install a fax server on site at each of the i3 Forum carriers that volunteered to participate in the testing, allowing each participant to send FoIP-based faxes to each other. Members of the SIP Forum FoIP Task Group installed an HMP FoIP fax server on site at each carrier’s location, largely completing that task in late 4Q2010. The tests, which consisted of a fax broadcast from each participant to all other participants, were performed over a 14-week period in the first four months of 2011.

Analysis and preliminary recommendations were completed over Q2-Q3 of 2011, and published in November, 2011. View the resulting “Phase I Testing” report.

The primary conclusion from this Phase I testing was that international FoIP based on G.711 pass-through and T.38 was not currently practical using current-practice call routing. The critical timing required of a successful FoIP call requires pre-qualified FoIP routes. SS-7, as it is currently being utilized by the international carriers, does not support the type of routing required.

Although ENUM and supporting standards would provide an elegant solution to the routing problem, the industry is unlikely to move with the coordinated purpose required for this to be anything but a too-distant option. The task group is, therefore, looking at recommending the SIP header “user=” to denote “user=fax” to give routing algorithms the option of explicitly routing a call over fax-qualified routes.

But while that recommendation is being debated, the task group has decided to move to Phase II testing to address the “fax-qualified” question. The plan is for the 16 test program participates to test in pairs, capturing logs from both the sending and receiving end of each call, supporting the forensic phase needed to give each carrier the information needed to support FoIP over their networks.

The task group’s goal is to make 2013 the year that the telecom industry made FoIP reliable in international calls.

Links to Archived Task Group Documents

Fax-over-IP Interoperability Task Group Document Repository, including, version 1.0 of the official task group Problem Statement, and presentations submitted for the founding Fax-over-IP Interoperability Workshop.

Fax-over-IP Interoperability Workshop Overview