[cisco-voip] SIP t.38 fax

[Nick Marus]

Interseting you mentioned this for I was having to look this info up this 
week as well and found this article:
 
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t3/dt_t38fx.htm
 What I understood is that it varies depending on the fax rate command. If 
you use fax rate voice it will take 64k, but if you use faxrate 9600 it only 
uses 24k.
 *Excerp:*
*Note* The fax call will not get compressed using the ip rtp 
header-compression command, because User Datagram Protocol (UDP) is being 
used and not Real-time Transport Protocol (RTP). For example, 9600 fax call 
will take about 24 kbps. 


 On 6/3/05, Brian Turnbow <b.turnbow at twt.it> wrote: 
> 
> 
> Hello All, 
> I am look ing to deploy a SIP network that needs to support fax and 
> looking into t.38 I found 
> 
> SIP T.38 Fax Relay 
> 
> •T.38 fax relay requires a 64-kbps transmission rate, the same amount of 
> bandwidth as a voice call with the G.711 codec. 
> 
> *
> http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide_chapter09186a00800b5dce.html
> *<http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide_chapter09186a00800b5dce.html> 
> 
> Do you need 64k for a fax transmission with via sip using a cisco gateway 
> ? 
> 
> Thanks 
> Brian 
> 
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> 
> 


-- 

Nick Marus
nmarus at gmail.com
homepage: http://www.nicholasmarus.com
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