T.38

T.38 is an ITU standard for sending FAX across IP networks in a real-time mode.
FAX messages are sent as UDP or TCP/IP packets.

• The IETF RFC RFC 3362 implements a media type called image/t38 for T.38 faxes.

From RFC 3362:

• Commetrex has completed significant interoperability testing in the T.38 Interoperability Test Lab.
• Dialogic White Paper: How does FoIP Work?
• Dialogic White Paper: Considerations for using T.38 versus G.711 for Fax Over IP

The Importance of T.30 ECM Error Correction Mode (ECM) in T.38 Deployments

One of the most important features of the traditional facsimile standard (T.30) is ECM error correction. The inventors of fax recognized that the audio quality of PSTN phone lines could not be trusted to be 100% error free – it was not uncommon to hear static, or the occasional pop or crackle on some fax calls. ECM error correction allows the sending and receiving terminals to compare notes at the end of each page, and selectively retransmit any data that was not received the first time around. This retransmission process is continued until the received page is certified error-free, and the transmission of the next page begins.

Remarkably, many T.38 implementations, including those of top tier carriers such as Level3, XO, Verizon etc have explicitly disabled ECM error correction. This problem is discussed in detail here. Don’t make this mistake! Be sure to enable ECM and insist on your provider or PBX vendor do the same!

Want to check to make sure you have ECM enabled? This handy ECM self-test tool can tell you in minutes.

T.38 with Fax Voip T38 Fax & Voice

FaxVoip Software develops solutions for the transmission of fax via the Internet Telephony (FOIP). The main emphasis has been placed on the transfer T.38 and audio via SIP, H.323 and ISDN CAPI 2.0. Fax Voip application operates with T.38 faxes via standard COM port interface.

What is VoIP? For your fax or voice application, it’s a Voice Fax Modem. You can setup your Fax & Voice program to operate with Fax Voip Virtual COM ports or virtual Fax Voip 14.4K TAPI Voice-Fax Modems. From the perspective of your VOIP internet network, it’s a SIP/H.323 client with T.38 and G.711 Fax support. From the perspective of your ISDN line, it’s CAPI 2.0 client with audio fax support. You can send/receive T.38 and audio (colour/black-and-white) faxes and voice messages without any hardware, using your favourite Fax & Voice program. Fax Voip is the ideal solution for the implementation of Fax and Voice Mailbox into SIP/H.323/ISDN network. You can use Fax Voip with your VOIP or ISDN-based PBX or with your SIP/H.323/ISDN Provider. Up to 100 virtual modems can be used simultaneously.

• Multiple SIP Registrations and Call Routing functions make your system the most flexible as well as allowing you to work with different SIP and H.323 providers simultaneously.
• Fax Voip supports Caller ID and Dial a Phone Number Extension features.
• You can send T.38, audio and CAPI faxes via Fax Voip Virtual Printer and receive faxes directly in TIFF, PDF or SFF files, and without limiting the number of incoming fax sessions. You can send audio messages. You can manage faxes and audio messages with Fax Voip Console.
• Fax Voip is a fully-functional system for sending faxes and audio messages via e-mail (Mail to Fax and Mail to Audio) and for receiving faxes to e-mail (Fax to Mail).
• Incoming Routing Methods (Route through e-mail, Store in a folder, Print) allow you to route incoming faxes to recipients on the network.
• Fax on Demand function allows callers to retrieve information via fax on the same call (from a fax machine).
• Fax Voip T38 Fax & Voice has been successfully tested with Microsoft Fax, CallStation, BVRP Classic Phone Tools 9, FaxTalk Messenger Pro, WinFax Pro, Venta Fax & Voice (include colour faxes) and many other well-known programs.
  Fax Voip has been successfully tested with CALLCentric, babyTEL, T38FAX, MondoTalk and many other VoIP service providers.

The last version 7.6.1 can be downloaded using the following link: http://www.t38faxvoip.com/downloads/t38fv7_6_1.zip

T.38 with Fax Voip Windows Fax Service Provider

Fax Voip Windows Fax Service Provider (Fax Voip FSP) enables Microsoft Fax and Windows Fax and Scan, which are built right into Windows, to send and receive T.38 and audio (over G.711 codec) faxes using your VoIP (SIP or H.323) infrastructure without any further cost.

Windows Fax Service and Windows Fax and Scan application is an integrated fax software included in all Windows versions. It is an extensible fax platform that you can use to deploy shared fax resources in your organization. Users within an organization can install a connection to a remote fax printer on a network fax server and send and receive faxes using shared fax devices located on the server, as well as from a local fax device attached to their computers. Fax administrators can configure, manage, and monitor these shared fax resources. Centralized management of server-based shared fax devices means easier management and maintenance, and lower costs. Fax users can send and receive faxes without the need to use manual fax machines, saving time and effort.

Fax Voip FSP replaces the standard Microsoft Modem Device Provider by the Fax Voip T.38/G.711FAX Device Provider. This allows you to use the Windows Fax Service most efficiently. In particular, the ECM (Error Correction Mode) is supported. The busy signal is also detected correct way. Using Fax Service Provider (FSP) instead of Virtual COM Ports and modems significantly improves the reliability of your fax system.

• Fax Voip FSP allows Windows Fax and Scan to receive Caller ID and Called Number (DID) – via Routing Information field.
• Multiple SIP Registrations and Call Routing functions make your system the most flexible as well as allowing you to work with different SIP and H.323 providers simultaneously.
• The Mail to Fax function will let you send faxes directly from your e-mail application. The body of your e-mail messages will act as the fax cover page, while any attached documents (e.g. PDF, TIFF, or TXT formats) will be converted into additional fax pages. Faxes can be sent to multiple recipients.
• Fax Voip FSP Routing Extension allows you to route incoming faxes depending on the Caller Number (Caller ID) and Called Number (DID), using the following fax routing methods: Route through e-mail, Store in a folder, Print. Custom routing for incoming faxes allows you to easy add any routing functionality by using custom application that is started after receiving a fax.
• Fax Voip FSP has been successfully tested with CALLCentric, babyTEL, T38FAX, MondoTalk and many other VoIP service providers.

The last version 2.3.1 can be downloaded using the following link: http://www.t38faxvoip.com/downloads/fvpfsp2_3_1.zip

T.38 with Fax Voip SoftPhone

Fax Voip Softphone is a powerful and unique SIP / H.323 software telephone that lets users make phone calls, record calls, play audio files into the telephone line as well as send/receive T.38 and audio faxes from one single software application using any Voice over IP (VoIP) telephony provider. Fax Voip Softphone supports Music on Hold, Call Transfer and Call Forwarding. Hairpin Call Transfer and Hairpin Call Forwarding (2 call legs). Audio and Fax panel allows you to send pre-prepared faxes and audio messages in one click. With Log Book you can easily view call history, view received and sent faxes and listen to call recordings and sent audio messages. The Phone Book provides a convenient place to store information about your contacts. Random Phone Calls function can be useful for your business, as well as for different testing purposes. The function allows you to automatically make repetitive phone calls to one or more target phone numbers. This function allows you to play audio messages into the telephone line, as well as to record phone calls. Using the Fax Voip Softphone Control Panel, you can easily configure the softphone according to your requirements.

Fax Voip SoftPhone has been successfully tested with CALLCentric, babyTEL, T38FAX, MondoTalk and many other VoIP service providers.

The last version 3.1.1 can be downloaded using the following link: http://www.t38faxvoip.com/downloads/fphone3_1_1.zip

T.38 with Asterisk

Built-in support for T.38

Digium’s Fax For Asterisk is a commercial facsimile (Fax) termination and origination solution designed to enhance the capabilities of Open Source and commercial Asterisk as well as Switchvox. Fax For Asterisk bundles a suite of user-friendly Asterisk applications and a licensed version of the industry’s leading fax modem software from Commetrex.

Asterisk 1.6 support G.711 and T.38 FAX origination and termination. T.38 gateway features are in Asterisk 10. Patch exists for Asterisk 1.8.

T.38 with Gridborg HMP Server (supported)

Gridborg HMP Server supports T.38 fax origination, fax termination and fax pass through. All of these options are available for both H.323 and SIP protocols. Gridborg HMP Server stores received documents in a multitude of formats and also enables sending of fax documents saved in TIFF and other formats.

Gridborg HMP Server has been successfully used with VoIP gateways from many vendors like Cisco, Planet, Patton, Sipura, and many others.

T.38 with open source ICTFAX

ICTFAX is an open source , multi-user and web based software solution for internet telephony service providers (ITSP) and businesses. ICTFAX is an email to fax gateway, supports G.711 faxing , PSTN faxing and T.38 origination and termination. ICTFAX based on open source Freeswitch, ICTCore and Drupal 7., ((ICTFAX is an email to fax, fax to email,web to fax gateway)),

ICTFAX supports T.38 origination and termination, T.30 origination, termination and gateway, G.711 Foip origination, termination and gateway capabilities

Released new version of ICTCore V 0.7.5 on March 12, 2017, with following improvements

• Twig based template added for gateway configurations and Application data
• Data and Token libraries updated
• Sip, SMTP and SMPP added as provider sub-type
• Multitasking support improved for Task and Schedule
• Namespaces and PSR-4 based auto-loading support added
• PHPUnit support added for unit testing

For more information please visit ICTFAX home site

T.38 with T38modem

What is T38modem www.openh323.org?

• It is not a modem.
• From a FAX application’s viewpoint (e.g. HylaFAX) T38modem looks like a class 1 FAX modem pool.
• From an IP network view point it’s an H.323 endpoint with T.38 FAX support. Recent versions also support SIP.
• From your viewpoint, it’s a gateway between a fax application and an IP network.

See also

• T.38 Fax 100% T.38 SIP origination and termination. Power-T.38 plan – Per minute rates with local and toll-free DIDs. Power-T.38 Ultra – Unlimited inbound and metered outbound.
• Fax Voip Software: T.38 and Fax over G.711 Solutions
• VoIPmonitor – T.38 to PDF packet sniffer
• www.Faxtest.info – Free Fax test service online – Send a test fax from your fax machine/T.38 devices to this number, check for errors and quality.
• Abilis The all-in-one VoIP/FoIP gateway with ISDN backup.
• Asterisk fax
• Asterisk T.38
• Asterisk T.38 Bounty
• AudioCodes explains fax relay methods in detail
• efax4asterisk : An AGI script which sends faxes to email addresses.
• FAX
• FAX over IP
• Fax over IP Gateways Reliable FAx over IP gateways for successful Fax over IP
• FaxLogic Hosted Internet Fax Fax over IP solutions (virtual fax, analog fax line replacement, SIP trunking for fax servers, hosted fax server)
• FaxxBochs 100% Reliable Fax over IP
• ICTFAX Email to FAX solution open source Email to FAX, FAX to Email faxing solution using foip (T.38) or pstn]
• Patton VoIP gateways T.38 ready
• Voys Telecom – Dutch T.38 provider with email-to-fax, fax-to-email and webfax support
• T.37
• T38modem
• Uniqall Gridborg HMP Server
• VBS Commercial Fax Server
• Voismart FAX Server T.38 and softmodem integrated into IP PBX
• T.38 design solutions for Fax server and softmodem developers