[SIPForum-discussion] SIP Faxing

[Steve Underwood]

A key question is 15% of what kind of calls fail? If you are talking 
about a public FAX server, open to all, you might well see 15% to 20% of 
failed calls from wrong numbers, voice calls to FAX numbers, etc. If you 
are making test calls into a well controlled server and get 15% 
failures, that pretty nasty. You should be getting less than 1% 
failures, even if the calls are sending tens of pages each.

Steve


On 08/13/2011 01:14 PM, Rohan Almeida wrote:
> 15% failure is too high. 2-10 % is on an average is acceptable.
> but again the fault might not be only in your system. the interconnect 
> devices might also be the cause.
>
> On Tue, Aug 9, 2011 at 9:52 AM, Greg Settle <gsettle at opentext.com 
> <mailto:gsettle at opentext.com>> wrote:
>
>     What is the topology?
>
>     SIP trunk - SBC/gateway - fax server?  If yes, who is the SIP trunk
>     provider?  Do they support T.38 FoIP?
>     T1/PRI - gateway - fax server?  If yes, which gateway(s) is involved?
>     Support for T.38?
>
>     Assuming a fax server is involved?  If yes, which fax server?
>
>     Generally, if T.38 FoIP is supported among all endpoints, and proper
>     testing was done to verify configuration among the components, SIP
>     faxing failure rates should remain low.  15% failure rate is high, and
>     points to weak links in the topology where FoIP standards (T.38)
>     are not
>     being met.  Attached is a document which may assist.
>     Greg
>
>     -----Original Message-----
>     From: discussion-bounces at sipforum.org
>     <mailto:discussion-bounces at sipforum.org>
>     [mailto:discussion-bounces at sipforum.org
>     <mailto:discussion-bounces at sipforum.org>] On Behalf Of Steve Underwood
>     Sent: Monday, August 08, 2011 9 <tel:2011%209>:47 AM
>     To: discussion at sipforum.org <mailto:discussion at sipforum.org>
>     Subject: Re: [SIPForum-discussion] SIP Faxing
>
>     On 08/04/2011 09:40 PM, Melissa Parsons wrote:
>     >
>     > Hello,
>     >
>     > Can anyone tell me what an acceptable failure rate would be when
>     > faxing over SIP? Currently we are averaging around 15%. This
>     number is
>
>     > high I would expect it to be somewhat higher than traditional faxing
>     > but not this high.
>     >
>     > Thank you,
>     >
>     > *Melissa Parsons*|Enterprise Systems Engineer
>     >
>     > *MarineMax, Inc.* ( 727.531.1700 <tel:%28%20727.531.1700> office
>     | (727.524-3954 <tel:%28727.524-3954> fax
>     >
>     > 18167 US Hwy. 19 N. Clearwater, Florida 33764 <tel:33764>
>     >
>     >
>     That's vague. Are you using A-law or u-law? Are you using G.726?
>     Are you
>
>     using T.38? Pretty much anything else you might use will give 0
>     success
>     rate, so I assume its one of those. The failure rate you get will
>     depend
>
>     on many factors. A high packet loss rate is a disaster for FAX. High
>     jitter levels for the packet delivery time can be too. T.38
>     implementations are quite variable in their behaviour, and not always
>     that compatible. Many quirks in the SIP signalling arrangements
>     exist in
>
>     various implementations, too. At the end of the day you'll get
>     somewhere
>
>     between 0 and 100% success, depending on all these factors. Between
>     servers in large data centres, connected straight on to the internet's
>     backbone you might be able to send FAXes all week without an error. In
>     really bad tributaries of the internet you might get a near 100%
>     failure
>
>     rate.
>
>     Regards,
>     Steve
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