This page serves to maintain a list of VoIP providers who offer T.38 origination/termination.

Confirmed

Do not add a provider to this list unless the provider explicitly advertises support for T.38 on their website (not just "fax support"). Please be aware that many providers which do not support T.38 will nonetheless list "T.38 support" as one of the features of the ATA's they sell. This does not count, and these providers do not belong on this list.

• Acepacket - Enterprise and Residential Broadband PBX/VoIP Services support T.38 - Hosted SBC with LCR and integrated billing system and SIP trunking - Contact Center (IVR- VoiceXML /Jabber / Outbound/Inbound Marketing implementation) - Prepaid/Postpaid CDR / Billing
• Alldaytalk - Support T.38 Fax Residential Broadband phone service provider.
• ContactTel Inbound DID's 100% T38 ,Pay as you go , or 9.95 monthly plan
• Endstream Communications - Cost-effective and high-quality T.38 service; inbound faxes are delivered directly to your email
• FaxDigits - Free personalised US FAX number in Iowa State. Fax to email attachment service in pdf format. Unlimited incoming number of faxes. VOIP T.38 codec enabled for internet faxing reception.
• GAFACHI (United States) - Pay-As-You-Go SIP provider, allows you to choose your method of fax, including T.38, through your on-line account management portal.
• Global Crossing Enterprise VoIP Services support T.38
• Intertel Full Confirmed T.38 support. Australian based provider, SIP, DID, 1300/1800 support, configuration and consultation.
• Interec Full T.38 support. SIP/H323 Cisco based. G729, G723, G711 SPAIN Sales Contact: laura@interec.com
• NodePhone (Australia)
• Logic Voice -The NEW Revolution in Voice Communications. Logic Voice provides leading voice, data, converged, and managed phone system for businesses and enterprises who need a proven, responsive, and cost-effective alternative to the phone company monopolies. US48 & Canada Termination only 0.6 cents per minute. Unlimited Inbound Local DIDs for only $0.99 per month. Toll free service for only 0.9 cents per minute
• OMEGA Telecom(Cyprus) - Premium Quality Worldwide Termination with CLI and T.38 fax support. T.38 Fax DID numbers origination and Fax2Email (T.38 and G.711) Service.
• onecentral(Netherlands) Corperate Voice and Fax service provider. Several T.38 based services, including soft-client.
• www.rangetel.com - Rangetel provides T.38 faxing to Canada and United States with full origination and termination to over 7000 rate centers. Rangetel fax service is used over cellular, satellite and broadband connections. Rangetel has the highest faxing success rate available. Contact info(@)rangetel.com for more information
• SWISSIPCOM(Switzerland) - SwissIPcom support T.38 faxing for outbound and inbound to all over europe and the US, we are terminating over 30,000 faxes every month over T38 protocol without a problem.
• MondoTalk - World wide T.38 support. Inbound and Outbound. Clear quality, Low rates. Call plans for many countries including utimed calls for Australia. No access fees, No contracts, No cancellation fees, No flag falls and No Connection fees. Too many features to mention here.
• T38Faxing.com . Termination provider only. Instant activation from customer portal that accepts Paypal and credit cards. No minimum, no commitments true PAYG service.

• Telecomservice (Austria) SIP/IAX2 provider, Austrian geo-numbers, PBX services, T38-Fax, PRI and BRI interface for existing PBX integration
• Thinktel Canadian Origination & Termination Expanded Footprint service in over 230+ rate centres, We support T.38 for both Origination and Term Contact stephen.halliday@thinktel.ca
• TieUs Technology - Support T.38 Fax - Business SIP Trunk services in 20+ major Canada Cities including Vancouver, Victoria, Calgary, Edmonton, Ottawa, Oshawa, Toronto, Winnipeg, Quebec, Montreal. DID origination and termination, Response Point IP PBX system. Hosted PBX solutions. SIP Trunking and IP Trunking with long distance package.
• NETWORTH TELECOM (France) - Networth Telecom is supporting T.38 fax outbound and inbound.
• http://www.transcom.net IPtransit is a Global voip transit network that supports T.38 by default for fax, (or G711 if that isnt suitable) PAYG if required
• WTS Telecom T.38 with G.711 failover Worldwide Termination for VoIP Fax. Support ATAs for termination. Fax Wholesale. Fax Blasting is allowed.
• VCCS - T.38 Fax Support including Fax2Email for IP-PBX based systems and ATA devices. VCCS is an SMB VoIP solutions provider based in Canada

The following providers offer T.38, but only at the wholesale level (they will not sell to retail customers and do not post pricing):

• Broadvox GO! SIP Trunking - Several multi-line SIP Trunking plans to choose from. All support T.38 faxing.
• Broadvox Wholesale - Competitive wholesale VoIP Origination and Termination pricing. Supports T.38 faxing.

Note: The "linkable confirmed experience" critera was removed since many providers who offer T.38 but do not advertise it (such as BroadVox) change their level of support over time.

Alternatives

• SatFax Networks (Canada) - SatFax Networks has a new method for fax over VoIP that is more reliable than using standard T.38. SatFax Fax Terminal Adapters will work over any form of High Speed Internet connection including Wireless Internet, Cellular Internet, and all bands of Satellite Internet services.
• ZCarrier Inc. ZCarrier Full T.38 support. SIP/H323, Wholesale VoIP Provider

Crippled

• Packet8 (United States) - Packet8 now support T.38 faxing service, although only with the provider-supplied ATA device ("The Packet8 fax plans are currently only available to Packet8 existing customers who purchase a new BPA410 phone adapter for Fax Extension"). For more info. Click Here.
• BroadVox Direct (residential offering, no longer offered) has T.38 support which was once reported to work with t38modem, but will no longer work with new accounts. You need a cryptographic credential which is entombed in the ATA they ship you, and the company is quite stubborn about never releasing that credential to the customer. So, basically, it's only T.38 if you use their ATA, and they're doing their darndest to use crypto to keep it that way.
• Draytel (UK) - acknowledged in their FAQ that they support t.38 fax relay. In conjunction with a HT386 and an SPA-2102, I have used them without any problems to transmit faxes to the US. Rate is about $0.02 per minute, pay as you go. You can test it for free (no commitment) with a two port FXS T.38 compliant ATA (HT386, SPA2102) and two different draytel accounts. Update (June 2007) DrayTEL has confirmed that they do not support T.38 on PSTN calls (see comment below)

Rumored

If you can provide a link to the provider's website indicating T.38 support for any of these entries, move it to the first list and link the evidence. If you can disconfirm, move them to the next list and include the date tested. Providers who claim that T.38 is coming "real soon now" should be disconfirmed due to the fact that almost all of those who make this claim remain in this state indefinitely.

• ComCanada Communications CRTC Registered, Provider of Hosted PBX, DID service, Toll Free, equipment sales, consulting, and retail/wholesale origination & termination. T.38 Supported ( but no confirmation). 1-877-697-VOIP
• FreeDigits (United States) - Rumored outbound-only support for T.38 SIP through faxdigits.com server ("recommends T.38-compatible adapter for outbound" but does not promise T.38 support). inbound faxes are converted to .pdf e-mail attach by the server
• Lingo
• Iristel website indicates that their adapters include T.38 support, but does not state that the service actually includes it. 100% Canadian Telephone Company. Unlimited Extended plan from $15.95. Iristel seamlessly bridges the gap between IP networks and the PSTN. Iristel's VoIP solution is ideal for Calling Card, VoIP carriers, CLEC's, Asterisk owners and virtual carriers requiring local service within Canada. Iristel also offers virtual T.38 faxing solutions both inbound & outbound.
• Trans National Communications International - We do and have interop tested T.38 fax support over SIP. We do not (to the best of my knowledge) confirm this on the site. I am part of the Tier III Engineering group, and I can tell you that it is functional. One potentially important note, we are a telecom wholesaler working through a reseller agent network. We do not do any direct retail sales. We also provide only business telecom services, no individual.

Disconfirmed

• teliax
• iaxtel
• VoiceMeUp
• Talkin2ya/Budgetphone (Netherlands) - say in their FAQ (in Dutch) that they support t.38 fax relay, however, a call to their help desk (december 2006) revealed that they do not support T38, in spite of what is mentioned their FAQ.
• IP Communications United States - National DID numbers, T.38 said to be included in basic plans. Working at one time, but as of April 2010, does not work at all. Any T.38 negotiation attempt returns "488 Not acceptable here."
• Gradwell - UK provider, confirmed no T.38 support. They had support at one point on some international numbers, but none anymore.

Wanted

• Providers offering both IAX-voice and T.38 (ie T.38 over SIP or H.323 — not necessarily over IAX)
• Telecomservice (Austria) SIP/IAX2 provider, Austrian geo-numbers, PBX services, T38-Fax, PRI and BRI interface for existing PBX integration
• Pay-As-You-Go providers with T.38 . Please go at babytel.net. We offer Pay as you go enterprise lines at 5$ per month. Our lines all support T.38.