[cisco-voip] recommended configuration for fax (MGCP PSTN Gateway, SCCP VG224)

[James Buchanan]

Your T38 is still disabled. When you changed it in UCM, did you reset the
gateway? You need the line "no mgcp fax t38 inhibit" for T38 to be enabled
in MGCP.


On Mon, Mar 3, 2014 at 3:28 PM, Michael Hamann <mail at mhamann.net> wrote:

>   Hello,
>
>  we are migrating a large Siemens PBX to a CUCM (9.1) environment with
> several 2921 MGCP (E1) PSTN gateways. We start now with the first branch
> offices where we plan to have a 2901 Voice router (MGCP) with SRST
> configured. SRST works as expected but we are not sure on how to provide
> analog lines (especially for fax maschines) in the branch offices.
>
>  So far we plan to put VG204 and VG224 in the branch offices, configure
> them with SCCP so that they can register with SRST in case of a WAN outage.
>
>  In our lab we are experiencing problems with sending and receiving faxes
> and I am not sure what the best configuration is. As far as I understand
> T.38 protocol based is not supported with SCCP and VGs.  So we decided to
> use T.38 NSE based. Here I am not sure on how this will work with our SIP
> Fax Server (XCAPI Interface confgured with T38). Since the amount of
> internal faxes is very low we could use softfax in this case...
>
>  So our call flow looks like this.
>
>  Fax Maschine <-> VG224 (SCCP) <-> CUCM (9.1) <-> 2921 (MGCP/E1) <-> PSTN
>
>  Our configuration an a *VG224* looks like this:
>
>  ----
>
>  voice service voip
>  fax protocol t38 nse version 0 ls-redundancy 0 hs-redundancy 0 fallback
> g711alaw
>
>  ---
>
>  Configuration on the C2921 MGCP:
>
>  ---
>
>  voice service voip
>  fax protocol t38 nse version 0 ls-redundancy 1 hs-redundancy 1 fallback
> pass-through g711alaw
>
>  ccm-manager fallback-mgcp
> ccm-manager redundant-host XXX
> ccm-manager mgcp
> no ccm-manager fax protocol cisco
> ccm-manager music-on-hold
> ccm-manager config XXX
> ccm-manager config
> ccm-manager download-tones
> ccm-manager sccp local GigabitEthernet0/0
> !
> mgcp
> mgcp call-agent XXX XXX service-type mgcp version 0.1
> mgcp rtp unreachable timeout 1000 action notify
> mgcp modem passthrough voip mode nse
> no mgcp timer receive-rtcp
> mgcp sdp simple
> mgcp fax t38 ecm
> mgcp fax t38 inhibit
> mgcp fax t38 ls_redundancy 1
> mgcp fax t38 hs_redundancy 1
> no mgcp fax-relay sg3-to-g3
>
>  ---
>
>
>  show mgcp:
>
>
>  ----
>  MGCP default package: mt-package
> MGCP supported packages: gm-package dtmf-package trunk-package
> line-package
>                          hs-package rtp-package atm-package ms-package
> dt-package
>                          mo-package mt-package sst-package fxr-package
> pre-package
>                          md-package
> MGCP Digit Map matching order: shortest match
> SGCP Digit Map matching order: always left-to-right
> MGCP VoAAL2 ignore-lco-codec DISABLED
> MGCP T.38 Max Fax Rate is DEFAULT
> MGCP T.38 Fax is DISABLED
> MGCP T.38 Fax ECM is ENABLED
> MGCP T.38 Fax NSF Override is DISABLED
> MGCP T.38 Fax Low Speed Redundancy: 1
> MGCP T.38 Fax High Speed Redundancy: 1
> MGCP Fax relay SG3-to-G3: DISABLED
> MGCP Fax relay ANSam suppression: DISABLED
>
>
>
>  ----
>
>  On CUCM we have disabled Cisco Fax and enabled T38 fax.
>
>  Is this configuration correct or did we now mix up T38 protocol based
> with T38 NSE ? A "show voice call summary" during a fax call show only a
> g711 connection...
>
>  Does anybody have a example configuration for our szenario ? What would
> be the recommended protocolls to use in this szenario ?
>
>  Thank you and kind regards
>  Michael
>
> _______________________________________________
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>
>
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