Reliable Faxing when using a SIP Trunk Provider
Why do we need this application?
Companies recognize the intrinsic benefits of using VoIP, many of them are already using it or considering migrating to it shortly. Most new PBX today are VoIP enabled and have many new convenient features available but it can also bring problems when it comes to faxing. Fax T.30 protocol has been working fine for decades over traditional pstn network and many companies still rely on traditional fax for sending or receiving important documents.
The problem comes from the fact that in VoIP the audio is digitalized, compressed and transmitted as packets over a not perfect IP network. Packet loss, jitter and compression would render a slightly distorted fax tone which many times is not recognized by the fax machines and, therefore, the fax fails.
Fortunately, T.38, the standard for sending Fax over IP, contemplates this problem and makes sending and receiving faxes reliable again even when using VoIP.
How does it work?
The fax machines do not change so we need to adapt the Voip network to support them.
Fax machines have to be connected to VoIP FXS gateways that support T.38. The gateway will recognize and decode the fax tones and instead of sending it as digitalized audio stream it will send the picture information as data packets. In the remote end there must be other T.38 enabled endpoint that will receive the data and reconstruct the audio tones before inserting to PSTN.
The T.38 protocol contemplates packet management techniques to enhance the quality transmission for the fax messages.
Implementation:
In order to implement this solution a VoIP fxs gateway with T.38 support is needed. The SIP trunk provider must support T.38 as well. If the IP-PBX does not support T.38 or at least act as T.38 pass thru then the VoIP call must flow directly between the endpoints that support T.38. Please contact ABP Tech for more details on equipment needed and help configuring it.
