[VoiceOps] Dynamic T1 Faxing over IP

Lee Riemer lriemer at bestline.net
Thu Dec 16 10:00:45 EST 2010

Can you list some devices that use the other versions and standards you 

On 12/15/2010 11:46 PM, Schwarz, Albrecht (Albrecht) wrote:
> This discussion is just at the surface.
> If you talk about fax over IP, then you should include the T.38 
> version, and there are 6 versions so far (T.38 v0 to v5).
> The majority of deployed ATA's seems to use T.38 v0 from year 1998, 
> which is an issue.
> The latest one is T.38 v5 (09/2010).
> If you talk about G.711 pass-through, then you should again 
> discriminate between
> a) V.152 VBDoIP with G.711 as VBD codec and
> b) pseudo-VBDoIP using G.711.
> The first one has a clear indication as VBD codec in the signalling 
> plane (like SIP, H.248, H.323, etc), which allows to distinguish G.711 
> as audio codec and G.711 in VBD mode.
> The second one is just a mess ("G.711 pass-through") due to the merge 
> of audio with VBD (... and different media configurations).
> All the requirements for FoIP and VBDoIP are e.g. summarized by *ETSI 
> TR 183 072 V3.1.1 (2010-09), *Emulation Services for PSTN Modem Calls.
> Which talks also about the interop issue.
> And one root cause are just different T.38 implementations ...
> Thus, any constructive discussion should address also that level of 
> detail.
> Regards,
> Albrecht
>     ------------------------------------------------------------------------
>     *From:* voiceops-bounces at voiceops.org
>     [mailto:voiceops-bounces at voiceops.org] *On Behalf Of *Richey
>     *Sent:* Donnerstag, 16. Dezember 2010 04:53
>     *To:* voiceops at voiceops.org
>     *Subject:* Re: [VoiceOps] Dynamic T1 Faxing over IP
>     The TA900s and 2431s will handle faxing, alarms, modems, etc fine
>     IF you do two things.  One you use point to point circuits between
>     you and the IAD.  The other thing is avoid sending these accounts
>     across sip trunks that traverse the internet.   We use a
>     combination of PRIs for local and SIP trunks for LD.  We route the
>     "data lines" so that their local and ld go out their closest
>     PRI.    If the customer wants to bring their own bandwidth or they
>     are offnet we won't support any kind of data calls.
>     Richey
>     *From:*voiceops-bounces at voiceops.org
>     [mailto:voiceops-bounces at voiceops.org] *On Behalf Of *Jeff Anderson
>     *Sent:* Wednesday, December 15, 2010 5:54 PM
>     *To:* voiceops at voiceops.org
>     *Subject:* [VoiceOps] Dynamic T1 Faxing over IP
>     We are experiencing a fair amount of heart burn attempting to
>     support faxing over our Dynamic T1 product. Some customers it
>     works great and others have frequent problems.
>     We currently support dynamic T1's using both Adtran TA900 series
>     and Cisco IAD2400 services routers. The customers fax machines
>     will connect to their PBX that has a PRI to an IAD/TA. We have the
>     IAD/TA configured for SIP signaling to an Acme SBC selecting T.38
>     as the preferred codec with fallback to g.711 pass-through. We can
>     force a slower speed, disable error correction, disabled VAD but
>     in the end still have very inconsistent results. From a network
>     perspective the QoS is matching and queuing correctly, the
>     circuits are clean and the IP SLA gives us no reason to believe
>     they are having any network drops or jitter.
>     I was wondering if others who have experience with faxing over IP
>     could share what they have learned works best or anything else
>     that may be helpful.
>     Any help is greatly appreciated.
>     Thanks,
>     Jeff
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