[VoiceOps] Dynamic T1 Faxing over IP

Lee Riemer lriemer at bestline.net
Thu Dec 16 12:06:29 EST 2010

Whoa, slow down there.  You mentioned "the majority of deployed ATAs 
seems to use T.38 v0...".  I simply asked what devices you knew used the 
newer standards.

The reason no one is talking about it at the level you are requesting, 
is because most of us probably have not heard of them.  We are in the 
trenches using readily available equipment, and if in the configuration 
of those devices requires us to match versions of the protocols you are 
describing, then we would include our experiences in this discussion.  
The thread owner stated two devices, and we replied with our experience 
in those.

We do not make the standards, we make them work.

On 12/16/2010 10:32 AM, Schwarz, Albrecht (Albrecht) wrote:
> The discussion of interoperability issues concerning fax/modem in 
> particular and PSTN X/modem calls in general was already topic in the 
> past two years in the correspondent experts groups, like
> - ITU-T Q.14/16
> - SIP Forum FoIP Task Force
> - ANSI TR 30.1
> - i3 Forum
> - MSF TC meeting and
> - IETF MMUSIC (concerning the usage of revised SDP Offer/Answer in SIP 
> for T.38, V.152).
> There isn't much value in repeating the same discussions in other 
> groups again.
> Starting point for product implementations is to point out their 
> standard compliance primarily against the recommendations by the 
> correspondent technology owners, i.e. ITU-T Q.14/16 in case of T.38 
> and V.152 and IETF MMUSIC in case of SDP O/A (via SIP).
> NGN / IMS compliant products on top must refer to 3GPP, ETSI TISPAN, 
> etc standards.
>     ------------------------------------------------------------------------
>     *From:* voiceops-bounces at voiceops.org
>     [mailto:voiceops-bounces at voiceops.org] *On Behalf Of *Lee Riemer
>     *Sent:* Donnerstag, 16. Dezember 2010 16:01
>     *To:* voiceops at voiceops.org
>     *Subject:* Re: [VoiceOps] Dynamic T1 Faxing over IP
>     Can you list some devices that use the other versions and
>     standards you mention?
>     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
>>     _______________________________________________
>>     VoiceOps mailing list
>>     VoiceOps at voiceops.org
>>     https://puck.nether.net/mailman/listinfo/voiceops

Lee Riemer
Director of Technical Operations
Bestline Communications, L.P.
Voice: 1+512.328.9095
Fax: 1+512.328.0038

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