Although FAX over Internet Protocol (FOIP) has been around for a few years, lately there has been a steady rate of adoption of this technology. A wide choice of VOIP Gateways, significant reduction of phone bills through least cost routing and added scalability options are just a few of the reasons why this technology is proving to be increasingly attractive for organizations that rely on faxing for their core business. Out of the box GFI FAXmaker can be implemented to utilize FOIP technology, delivering highly reliable faxing over VOIP networks using T.38 in conjunction with either SIP or H.323 protocols.

Depending on the VOIP setup, configuration and troubleshooting of VOIP Gateways can be tricky. In this short article I will be discussing tips & techniques to use during configuration and troubleshooting issues with FOIP.

Key FOIP components

The basic VOIP setup would consist of the fax server (GFI FAXmaker), the FOIP Software (Brooktrout SR140 or TE-Systems XCAPI) and the VOIP Gateway. The first step is to check the configuration of the VOIP Gateway settings according to the manufacturer’s recommendations including the specific settings for the FOIP protocol to be used (SIP or H.323). Then on the FOIP Software, you need to insert the correct settings to be used with the VOIP Gateway. Normally just the VOIP Gateway IP is needed to be configured in the FOIP Software for the faxing to work however some other configuration tweaks may be necessary.

Base investigation

The advantage of using FOIP is that it is IP based and you can run a network sniffer tool to troubleshoot problems. A very useful tool in such cases is Wireshark.

Here is the procedure to sniff and analyze the FOIP calls:

  1. Download and install Wireshark on the fax server. The machine running Wireshark can also be a separate machine connected to an Ethernet hub between the machine running the FOIP Software and the VOIP Gateway.
  2. Run Wireshark and choose Capture -> Interfaces. Click start next to the Interface used by the FOIP Software.
  3. Send/Receive a test call. When finished, stop the capture.
  4. Click in Telephony -> VOIP Calls to open a list of all the VOIP calls which occurred during the capture. Select the call and click on Graph/Flow.

Captures can be saved to a *.pcap file and sent to GFI Support personnel for further analysis. It is important to specify the make and model of your FOIP Gateway and which FOIP Software is being used.

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