I have been referencing people to an article I wrote recently when they have come to me looking for basic information on fax over IP principles and solutions. So, I thought I would share that article here as well for anyone new to fax over IP or for those looking for a broad overview of current FoIP technologies.
http://www.cisco.com/web/services/news/ts_newsletter/tech/chalktalk/archives/200808.html
This article explores basic fax over IP technologies from passthrough to relay to T.37 Store-and-Forward fax and even touches on basic Group 3 fax standards (discussed in the previous blog post) and fax servers. I would be interested in any questions or comments about the article including topics that you want to see discussed in future blog posts.
-David
David Hanes, CCIE 3491, is an engineer within Cisco's Customer Advanced Engineering (CAE) team, where he assists with fax over IP (FoIP) solution design, troubleshooting, and new product testing. David is the co-author of the book Fax, Modem, and Text for IP Telephony and regularly speaks and provides training on Cisco FoIP solutions. Since joining Cisco in 1997, David has held various positions within the Cisco TAC organization including Team Lead for the Multiservice Voice Team and TAC Escalation Engineer for VoIP technologies.
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RightFax Server
Hi David,
I am in the process of implementing a Rightfax server into my CUCM 6. environment. I have a centralized CUCM cluster with remote MGCP gateways. I found a paper from Dialogic on recommended configuration but it is not very well written and leaves out a lot of detail and background. Their configuration implements a ICT between the fax server and CallManager and forces gateways to use t.38 fax relay (MGCP fax t38 gateway force). I found that this configuration breaks my ATA attached fax machines - I think because ATA's do not support t38 fax relay.
Are there an Cisco docs on best practice implementation of callmanager and Rightfax servers?
Thanks,
Bill
RIghtFax Server
Hi Bill,
You should add the RightFax server as an H.323 gateway and not use an ICT. This is incorrect in the Dialogic document. While an ICT will probably work, this is not its intended purpose and not recommended by Cisco.
The MGCP fax configurations can be a bit tricky. With the ATA you must keep "mgcp modem passthrough voip" configured. You are correct that ATAs do not support T.38. The command "mgcp fax t38 gateway force" is only applicable to T.38 switchovers using Cisco proprietary NSE (Named Signaling Event) packets. Therefore, it is not necessary for communicating with fax servers. You typically only need this command when communicating via NSE-based T.38 with SCCP gateways.
As far as I know there are not any Cisco design documents specifically for integrating RightFax servers with CUCM. The closest thing would probably be a design chapter and fax servers chapter in my book, "Fax, Modem, and Text for IP Telephony". However, I am more than happy to answer questions for you here as I periodically check my blog.
Regards,
David
RightFax
David,
Thanks for the answer. You cleared up a lot things for me. I bought your book last week. Based on that I realized what the MGCP fax t38 gateway force command did and promptly removed it from my gateways. I was still confused about the ICT but now you have answered that also.
My big regret is that I didn't buy your book sooner. Thanks for writing it and thanks for the help.
Bill
RightFax
Hi Bill,
No problem. I am glad to hear that my book was helpful. If you have any additional questions, please do not hesitate to contact me.
Regards,
David