IP Communications T.38 Fax Support

T.38 is an ITU standard for sending FAX across IP networks in real-time.  T.38 faxing has a lot of confusion and mystery surrounding it these days.  The question, “Do you support T.38 faxing?” is becoming more and more difficult to answer with a definitive, “Yes!”.  This is primarily because T.38 capabilities and implementations vary greatly between VoIP providers as well as VoIP hardware vendors.  So, we tend to answer the question, “Does IP Communications support T.38 faxing?” with a resounding “Yes”, always followed by, “but it depends on your setup”.  Our technical support team is always more than willing to work with your individual requirements to work around any product specific hurdles you may stumble upon. We also can provide you a free test number for you to test with before actually signing up. 

How T.38 works through our network

IP Communications transports T.38 through our network by allowing the T.38 UDPTL data to pass through to a T.38 PSTN gateway or other T.38 SIP device.  Upon detecting a fax tone, our network will send a re-INVITE to attempt to switch to T.38. If the re-INVITE fails, another re-INVITE will be sent to attempt to switch to G.711 ulaw (if not already ulaw).

Have more questions about T.38 Faxing, contact us.