[cisco-voip] VG224 with Fax Machine going out Verzon Business SIP trunk via CUBE

[Nick Matthews]

Last I heard Verizon was offering a 'beta' to customers interested in
using T38.  As of a few months ago it wasn't something they supported.
 You won't be able to fax in G.729.  The equivalent is T38.

Modem passthrough is done via NSEs, and unless the Verizon equipment
is also set up for a Cisco proprietary method of doing faxes it won't
work.

What you're looking for is fax pass-through:

voice service voip
fax protocol pass-through g711ulaw


If you're doing SIP-H323 or SIP-SIP CUBE I would go to 20T or later.
You will want these commands (with the allow-connections as needed)
also:

H323-SIP:

voice service voip
 h323
  empty-capability

SIP-SIP

voice service voip
  sip
   midcall-signaling passthru



-nick

On Tue, May 26, 2009 at 5:33 PM, Craig Staffin <craig at staffin.org> wrote:
> Jason,
>
> So far in my experience with VZ business SIP has not been the best with
> faxing.
> They do allow fax pass-through however sometimes the CUBE router has
> problems switching from a G729 codec to G711 mid stream.  However I can
> honestly say that I have never gotten faxes to work reliably over the
> verizon network.
>
> The default for Verizon SIP is G729 and once fax tones are detected it will
> send a new INVITE message asking for G711 ONLY be aware of this as I ran
> into problems where the dial peer was only coded for G729 and this would
> lead to call silence on the call.
>
> Some debug SIP messages would be useful to see if the call was detected as a
> fax call by the Nortel softswitches that verizon uses.  If it was you should
> see a INVITE messages a few seconds into the call.
>
> Post back once you have some debugs as I have gotten far to familar with
> troubleshooting verizon SIP issues :)
>
> Craig
>
>
> On Tue, May 26, 2009 at 2:52 PM, Jason Aarons (US)
> <jason.aarons at us.didata.com> wrote:
>>
>> Customer has a fax machine on VG224/SCCP/Modem Passthrugh out CUBE
>> 12.4/CallManager 7.0(2) running into Verizon Business SIP trunk.  The fax
>> machines are having some issues (I can use analog phone to call out fine)
>>  and I’m checking on modem passthrough with Verizon, but wonder if any else
>> is using Verizon Business for SIP trunk and what your faxing milage was? Did
>> they support G711 and modem-passthough, etc? Also checking QoS, etc.
>>
>>
>>
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