Service Provider T.38 Offload
Stop Wincing When Customers Ask About Fax
Offload fax from your network with Service Provider T.38 from T38Fax. Wholesale pricing, certified softswitch integrations, and support that actually escalates.
The Fax Question Is Costing You Deals
Your sales team dreads it. That moment in a demo when an enterprise prospect asks: “What about our fax machines?”
You know the options aren’t great:
Option 1: Tell them to keep a POTS line for faxing. In 2025. With a straight face. Watch them get billed by a competitor for something you should be providing.
Option 2: Promise that T.38 pass-through will “probably work.” Then spend the next six months fielding support tickets about failed faxes, garbled pages, and calls dropped mid-transmission.
Option 3: Just say you don’t support fax. And lose the deal to someone who claims they do.
Here’s the part your carrier won’t tell you: if T.38 pass-through isn’t working, the problem is almost certainly upstream. You’ve probably configured your system correctly. The issue is that there’s not a single carrier — not even Level3 — who does T.38 well. Their implementations are inconsistent. Many have disabled ECM error correction entirely to save processing power. Quality varies wildly depending on which route handles any given call.
Your customers don’t blame the carrier. They blame you.
Service Provider T.38 Offload
What if you could officially support fax — reliably, at scale — without becoming fax experts yourself?
That’s what Service Provider T.38 Offload is. The implementation is trivial:
- Establish a SIP trunk to T38Fax — Simple interconnect, same as any other carrier relationship
- Route fax traffic to us — Keep voice on your existing carriers; send fax our way
- Port fax DIDs to T38Fax — Your customers' fax numbers move to our network
- We handle the rest — Your customers' equipment interacts with our T.38 stack, not your carrier's
The hard part — building reliable T.38 — we’ve already done. We built our network specifically for fax. We collocate media gateways inside carrier networks and terminate G.711 audio directly to the PSTN over a single optical hop. Your customers get consistent, predictable faxing. You get to stop dreading the fax question.
Four Reasons Service Providers Choose Us
Consistent T.38
Our T.38 stack runs on every call. We collocate media gateways inside carrier networks—your fax server talks to our gateways, not some unknown upstream provider. No variable routing, no mystery failures.
ECM Error Correction
Most carriers disable ECM to save processing power. We insist on it. Without ECM, fax pages can arrive corrupted with neither side knowing. The word "facsimile" means exact copy—that requires ECM.
Security & Compliance
SOC 2 Type II certified. HIPAA compliant. Optional VPN tunnels. We never store PHI because T.38 is real-time. When compliance asks about fax infrastructure, you'll have answers.
Premium Support
Fax industry veterans who diagnose with protocol analysis, not superstition. We understand T.30 negotiation, ECM partial page retransmission, and why your fax failed at page 47 of 200. Unlimited support included.
What Service Providers Say
"I have been submitting ports to T38 for over 2 years now. Stefanie and Karen in porting have always gone above and beyond to ensure our ports are submitted in a timely manner. They are always a delight to work with and have provided the highest quality of service one can expect from a provider."
— Jennifer Di Lorenzo, Porting Manager, Fusion Networks"Darren and Morgan have both provided superb support for us as we've expanded our operations and grown our footprint. They often go the extra mile and work with us in cooperation to help us deliver to our customers the best fax platform possible. On a scale of 1–10, I would rate their support at a 10 for sure!"
— Tim Winn, Manager, Technical Services, DRNS Software SolutionsWorks With the Platforms You Already Run
The offload model is SIP-native — if your platform handles standard SIP trunking, interconnection is straightforward. We’ve completed certified integrations with the most widely deployed service provider platforms.
Certified Softswitch Integrations
- NetSapiens
- FreeSWITCH
- Asterisk / FreePBX
- Cisco BroadWorks
- Telinta
- 3CX
- Metaswitch
Interconnect Models Supported
- SIP trunk interconnect
- DID porting
- Toll-free number porting
- Wholesale volume pricing
Not on the list? Reach out — if your platform supports standard SIP, we can make it work. Configuration guides for certified platforms are available in our knowledge base.
Running a fax server yourself? See our Enterprise Fax Servers page for RightFax, HylaFAX Enterprise, GFI FaxMaker, and more.
View Enterprise SolutionsFrequently Asked Questions
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The model is simple: establish a SIP trunk to T38Fax, route your customers’ fax traffic to us, and port their fax DIDs to our network. From that point, your customers’ fax equipment interacts directly with our T.38 media gateways — not your carrier’s inconsistent implementation. You claim T.38 support; we handle the T.38. The arrangement is completely transparent to your end customers.
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T.38 pass-through means your system relays T.38 traffic between your customer and your upstream carrier — you’re dependent on the carrier’s T.38 quality, which is typically poor. With T38Fax offload, your customers’ fax traffic terminates on our network, not the carrier’s. We run our own T.38 stack, collocated inside carrier networks, and terminate G.711 audio directly to the PSTN over a single optical hop. The result is consistent, predictable T.38 — not whatever the carrier happens to deliver that day.
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Yes. The offload is invisible to end customers. They dial and receive faxes as normal. Their equipment negotiates T.38 with our media gateways. Your company remains the service relationship — your customers don’t see T38Fax unless you choose to tell them.
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Yes. We offer wholesale pricing to service providers who can meet certain volume commitments. Pricing is based on usage rather than fixed seats. Contact our team to discuss your call volume and get a wholesale rate.
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We’ve completed certified integrations with NetSapiens, FreeSWITCH, Asterisk/FreePBX, Cisco BroadWorks, Telinta, and 3CX, among others. In practice, if your platform supports standard SIP trunking, the interconnect is straightforward. Our knowledge base includes documented configuration guides for the most common platforms.
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You escalate to us, and we actually investigate. Our support team diagnoses with protocol traces and T.30 analysis — not guesswork. We identify whether the issue is in the T.38 negotiation, ECM handling, network path, or the customer’s equipment. You get a real answer you can pass along, not a suggestion to lower the fax speed and hope for the best.