Fax over IP - FoIP

Fax over IP can be done in many ways, either realtime or store-and-forward


  • Transmission of a fax audio stream over a VoIP protocol, like SIP, IAX, H.323. This requires an uncompressed 64 kbit codec to have any chance of working, resulting in the need of around 80 kbit bandwidth. For a number of reasons it may or may not work even then.
  • Fax over IP with a special protocol designed for this application. The key standardised protocol for this is T.38.

Store and forward

  • A FAX, from a FAX machine, is decoded and stored by a FoIP gateway. It is then sent, using SMTP or a similar transport, to another FoIP gateway where it may be sent out to a destination FAX machine. The key standardised protocol for this is T.37.

Potential FoIP Drawbacks

Faxing over VOIP connections can be unreliable because fax data needs to be sent in real-time. The compression of the data required to transmit over IP can result in lost packets, and faxes failing to send. To improve reliability, some online fax solutions have switched to PSTN (public switched telephone network) lines which are intended for fax. This transmission method boasts over 99% deliver-ability.

FoIP Resources

All about FoIP As IP networks and VoIP adoption expands, and traditional Public-Switched Telephone Network (PSTN) phone services change, organizations with paper-intensive communication processes increasingly look to Fax over IP (FoIP) as part of their solution. is a bold initiative which provides VoIP providers, integration specialists and their clients with the most instrumental offerings of FoIP components and solutions, including Audio Codes, Alcatel, Avaya, Biscom, Cisco, Commetrex, Dialogic (Brooktrout), EtherFax, Faxback, Faxcore, GFi, Open Text (RightFax), SagemCom (XmediusFax), ShoreTel, and TargetFax.

FoIP Software

T.38 with Fax Voip T38 Fax and Voice

FaxVoip Software develops solutions for the transmission of a fax via the Internet Telephony (FOIP). The main emphasis has been placed on the transfer T.38 fax using SIP and H.323.
Fax Voip application operates with T.38 faxes via standart COM port interface.
Fax Voip T38 Fax & Voice - Fax and Answering Machine for your SIP/H.323/ISDN CAPI 2.0 line. Multiple SIP Registrations. Call Routing. Voice Fax Modem for your Fax & Voice software. Color faxes over VOIP and ISDN. Incoming Routing Methods. Fax-On-Demand.
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 (color/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 allow you to work with different SIP and H.323 providers simultaneously.
Caller ID and Dial a Phone Number Extension features are supported.
You can send T.38, audio and CAPI faxes via Fax Voip Virtual Printer and receive faxes directly in TIFF, PDF or SFF files. You can send audio messages. You can manage faxes and audio messages with Fax Voip Console.
Fax Voip allows to send faxes and audio messages via e-mail (Mail to Fax and Mail to Audio) and receive 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 allow callers to retrieve information via fax on the same call.
Fax Voip T38 Fax & Voice has been successfully tested with Microsoft Fax, CallStation, BVRP Classic Phone Tools 9, FaxTalk Messenger Pro, WinFax Pro and many other well-known programs.
Please, visit the Fax Voip home page at
The last version 7.6.1 can be downloaded using the following link:

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 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 and many other VoIP service providers.
Please, visit the Fax Voip FSP home page at
The last version 2.3.1 can be downloaded using the following link:

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..
Please, visit the Fax Voip Softphone home page at
The last version 2.3.1 can be downloaded using the following link:

Start here

Service Providers

  • 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.
  • Foiply Newest fax over IP technology. Email to Fax. Fax from any internet device. US based company. Simple pricing plans. No contracts or set up fees. One of the most reliable solutions.
  • FaxxBochs Fax-Over-IP - The most reliable Fax-Over-IP service in the US and Canada
  • ClicktoFax Online Fax - Lowest Cost Fax Service Provider with complete DID coverage US/Canada
  • SendaFaxFree Free Online Fax - Free Outbound Faxing to US and Canada
  • Live-Tech ZippyFax Solution Provider | FoIP & VoIP Sales - Service - Support | Worldwide Support | Get Faxes Emailed To Your Domain | TalkSwitch PBX Sales & Support
  • One Touch Global Technologies Industry Experts. More than 19 years of experience. Fax Server, Fax Service, Fax Broadcast, Host Fax, Email 2 Fax, FoIP Implementation and more
  • FaxLogic Hosted Virtual Fax Solutions Offering a wide range of branded and white-label fax solutions: virtual fax (fax-to-email, email-to-fax, web-fax, fax store/archive), analog fax line replacement, SIP trunking for fax servers, and hosted fax servers for single-user, group, and enterprise environments. Experts in fax technology and services since 1993.
  • Fax-to-Email - Fax Service Provider in Iran
  • FreelyCall provides FoIP part of its VoIP services, so you are billed similarly as if you're making a VoIP call. You can as well receive faxes over your account for free. By default, T.38 mode is enabled, however when the sending or receiving entity does not support it, tone mode (CNG) can be used with g.711 codec to reliably transmit the fax.

See also

Created by: oej, Last modification: Tue 16 of Jan, 2018 (16:41 UTC) by faxvoip
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