Fax/Modem over VoIP/non-physical phone line

watty

If my phone line eircom number is not ported soon I'm junking it anyway. Esp now that I can fax and modem on my wireless VOIP.

It is now a 1 year anniversery of starting to port line.

I have needlessly paid nearly 250 Eur. because I didn't know till a month ago that I had to cancel my CPS talkTalk.

TalkTalk frightend me by sending a "Welcome" letter instead of a "Goodbye" letter when they cancelled me.

wexfordman

watty wrote:

If my phone line eircom number is not ported soon I'm junking it anyway. Esp now that I can fax and modem on my wireless VOIP.

It is now a 1 year anniversery of starting to port line.

I have needlessly paid nearly 250 Eur. because I didn't know till a month ago that I had to cancel my CPS talkTalk.

TalkTalk frightend me by sending a "Welcome" letter instead of a "Goodbye" letter when they cancelled me.

Watty,

How do you manage to use modem on your VOIP, and will this work with Sky ?

Regards,
Wexfordman

crawler

We should have it working for Sky and Phonewatch etc soon....The system used T.38 by default but we have changed it to PCM. It's working we just dont want to tick the boxuntil it's stress tested etc...

HTH

watty

wexfordman wrote:

Watty,

How do you manage to use modem on your VOIP, and will this work with Sky ?

Regards,
Wexfordman

You plug the modem, sky box or fax into the phone port on your VOIP provider's ATA.

I can't g'tee it works for everyone or anyone. It depends of several things all being good!

:: You have a VOIP supplier that supports PCM (uLaw usually) rather than just low bit rate Codec. The low bitrate (e.g. G.729) should be default. In any case SIP settings MUST match your VOIP provider's Gateway.

:: Your SIP/ATA can automatically detect a Modem is being used and change codec.

:: T.38 is ONLY a Fax Emulation, it needs the same version at each end (your ATA and the suppliers gateway). It won't work at all for phonewatch or Digibox or dialup and if enabled may erratically stop them working. T38 does not send a digitised version of the modem signal. It sends ordinary TIF image file data in frames across the internet between two Fax emulators. This is why it can't work for anything else.

:: Your own SIP/VOIP needs setup correctly. Obviously a PC only implementation VOIP is no use. You need a standalone VOIP adaptor.

:: Avoid NAT traversal. Your SIP/ATA needs to be builtin to your router or on WAN side of your Firewall.

:: You need low jitter and less than 2% packet loss, especially for Fax. The actual ping time is not really important. Adaptive echo cancellation in modems gets very confused it the latency changes. Called QOS.

:: The likelyhood of this working using a different provider for VOIP than your network provider is lower. If the BB provider and the VOIP provider are the same it means the data is not really going "across the Internet".

:: If the BB provider somehow is provisioning the SIP on WAN directly and can implement QOS for VOIP, then it is not affected by bittorrants, video streams etc, otherwise these can knock out your connection or lose the fax.


It will be interesting to see what announcement on this Digiweb makes. QOS is not an issue that many 3rd party VOIP providers like discussed.


"My VOIP" did let me send an email via my digibox to Sky. This may be of no significance for anyone else's VOIP.

I like experimenting

Using PCM codec on arbitary BB and 3rd party VOIP supplier is not likely to work for Fax, hence the invention of T.38, it is not very likely to work at all for non-Fax modem as implementing PCM codec would be unusual and in any case PCM does not work at all well across aribitary route on Internet.

watty

I'm sure this started off as a comment about eircom but it seems to have been cut off, rooted and taken on life of its own.

cgarvey

A.K.A. you went off on one!

So using PCM wont work for traditional fax machines (T.38's for that), but will work for modems/dialers (like alarms/SkyDigibox/dialup modems)?

watty

No it's not as simple as that,

PCM will work for ALL kinds of modems, inc Fax. if you have good QOS or low packet loss and low jitter.

T.38 generally won't work at all. If it does work, it will ONLY work for a fax transmission.

And you DO need Dail up Internet on Broadband!!

Say you had/have an eircom account or some other ISP different to Broadband supplier and want to change something like add an email address or non-web access hosted data or settings? Then you need to be logged in via that ISP. Using a dialup modem on your VOIP solves that!

If you are using a different supplier for VOIP and Broadband, then PCM may not work for anything. T.38 *Might* work as it only sends IP data, not digitised modem squeeks on the net. You'd need a VOIP/SIP/ATA with 100% compatibility to your VOIP suppliers PSTN voice gateway, probably supplied or provisioned by them. The local ATA and the remote PSTN gate then both have to emulate Fax Machines. There is another two ways to do Fax.

Fax relay. Not real time.

PDF or TIF email gatway. Not real time either, but you only need an email client and don't need Fax machine or even VOIP.

Altreab

watty wrote:

No it's not as simple as that,

PCM will work for ALL kinds of modems, inc Fax. if you have good QOS or low packet loss and low jitter.

T.38 generally won't work at all. If it does work, it will ONLY work for a fax transmission.

And you DO need Dail up Internet on Broadband!!

Say you had/have an eircom account or some other ISP different to Broadband supplier and want to change something like add an email address or non-web access hosted data or settings? Then you need to be logged in via that ISP. Using a dialup modem on your VOIP solves that!

If you are using a different supplier for VOIP and Broadband, then PCM may not work for anything. T.38 *Might* work as it only sends IP data, not digitised modem squeeks on the net. You'd need a VOIP/SIP/ATA with 100% compatibility to your VOIP suppliers PSTN voice gateway, probably supplied or provisioned by them. The local ATA and the remote PSTN gate then both have to emulate Fax Machines. There is another two ways to do Fax.

Fax relay. Not real time.

PDF or TIF email gatway. Not real time either, but you only need an email client and don't need Fax machine or even VOIP.

Is it possible to send and receive faxes using a broadband connection?

watty

Yes, that's what I have been explaining.
re-read Today, 14:21

Basically you need either:

1) A 3rd party VOIP supplier that 100% supports T.38 themselves and supplies you a box with phone port that has the same flavour of T.38. This won't work for any other kind of modem use like dialup Internet, Digibox or Phonewatch.

OR
2) VOIP supplied BY your existing Broadband supplier that has box (SIP/ATA) with a phone port. It automatically switches from low bitrate high compression for voice (talking) to high bitrate PCM codec for ANY modem squeaks & squawks (Fax, Phonewatch, Digibox and dialup Internet).

Solution (2) is nicer with a good network supplier. It adapts to talking or Modem use and supports ANY kind of modem usage.

Solution (1) is inflexible, you get charged extra compared with a voice only VOIP account. It ONLY does talking & Fax. If packet loss is more than 6% this won't work either!

If you have DSL and it ISN'T LLUed, then using the regular phone line for fax may work best. Though of course for international calls your VOIP supplier *MIGHT* be cheaper, it might not be as it may still be an international call for your VOIP supplier. If you are using an international VOIP supplier with IP <--> PSTN gateways in the far of country, then the fax probabily will fail as it is unlikely to survive the variable pings of the non-deterministic routing

cgarvey

Right so, PCM all the way (and a bit of SIP no-how client side). Que Digiweb.

Solair

European telephone lines (including Ireland) use aLaw PCM, not u-law which is a North American and Japanese standard.
Some faxes in particular will not behave properly on u-law lines.
aLaw will actually give you better sound quality too as it has a better dynamic range.

http://en.wikipedia.org/wiki/A-law_algorithm
http://en.wikipedia.org/wiki/Mu-law_algorithm

watty

Both are 8 bit.
You have to use the same law at each end. A PCM codec on a SIP/ATA box for VOIP never ever connects direct to ISDN / PSTN PCM. It has to go through a voice gateway.

They are both simply curves to achieve some simple dynamic range compression, larger signal level has less bit resolution than small signal level variation. Both work more or less equally well or poorly with Fax providing you have the same at each end. A mis-match will cause some slight distortion of speech but cause total failure of higher baud rate modems.

IP network with PCM on it is not at all like ISDN /PSTN with PCM on it. Much inferior!

A-Law gives slightly more dynamic range
u-Law gives slightly lower distortion for smaller signals

Obviously anyplace I said uLaw you may substitute A-Law. Any VOIP SIp to Gateway is a closed system. Whichever is used needs to be the same on all their network.

Peer to Peer SIP calls is another matter, but Faxes and Modems are only used with PSTN numbers not peer to peer IPs


And you don't want to use PCM for ordinary speech as the ISDN 64K equivalent PCM on IP network can be 90K each way! Ordinary talking on VOIP uses a non-PCM codec using less than 6kbps typically. PCM is not robust for IP networks without extra overhead.

Solair

Phonewatch / other monitored alarms should be quite VoIP friendly. They usually use incrediably old-tech very slow modems as they only transmit a line or two of data at most.

Usually their signals are pretty robust.

Sky Boxes on the otherhand use high speed modern modems, so you could be in trouble there.

Wouldn't it be:

Your phone to ATA (PCM aLog)---(BlueFace SIP server)---(Voice gateway) to ISDN (aLog) [into the PSTN]

I'd assume you'd want aLog on your end as the signal coming out the other end is also aLog

Using uLog at your end would only add another layer of potential problems?

watty

It doesn't matter what ANY VOIP operator uses nor what the PSTN uses. Thats what a gateway is for, to interface.

A high speed modem or Fax probably won't work on Blueface:
1) They are 3rd party, so call is on Public Internet (jitter, packet loss)
2) may not support G.711

If you are with Blueface you have to use uLaw or ALaw as they decide for thier Voice Gateway IF they even support G711 at all.

The Client Customer NEVER choses the Codecs. The VOIP operator decides what is available.

AFAIK many phonewatch fail to connect as they are on pairgains and Phonewatch uses Dialup internet.

Most Monitoring systems are 33K or 56K modem.

Even a high speed will fall back to 19,200 potentially. My VOIP reports 42K+ but probabily that is compression on a 33K mode. True V.90 56K should be impossible.

G.711/PCM (uLaW vs Alaw is not the issue) is only going to be reliable for Modem or Fax if the call does NOT go via public internet, i.e. your own ISP carrier is also the VOIP supplier. Gateway is essentially on same (W)LAN.

You don't really pick any Codecs as the VOIP /ISP provisons the SIP.

Solair

eircom phonewatch, at least the older style wirefree alarms, use a Bell 103 standard modem!!!

It's a standard first introduced in 1962.
300bps

watty

I think they must have upgraded as some phonewatch don't work due to pairgains

watty

Integrated VOIP rates as best quality:

What Keynote found was that Comcast and Time Warner Cable outranked the rest in terms of audio quality and helped bring the entire category's overall score up to above a 4.0 Mean Opinion Score--considered toll-grade quality. But the company found that even other VoIP performers were edging up in quality, getting scores comparable to GSM phones for quality.

From http://telephonyonline.com/voip/commentary/voip_quality_091906/

Providers with comparable VOIP solutions to Comcast and Time Warner Cable are integral* VOIP solutions here are Magnet fibre/LLU, Smart LLU, Digiweb Metro and Chorus/NTL Cable(UPC Chello).

(*integral: VOIP SIP/ATA hardware and VOIP provision part of the broadband package from the one supplier, i.e. Smart or Blueface on UTV/BT/eircom BB isn't integral).

Does caseyVision do builtin VOIP on their cable modem?

Comcasat and TimeWarner are probabily using DOCSIS 2.0 cable spec which has separate QOS management for VOIP. Digiweb and UPC use this for QOS on their cable modems (Metro is cable broadband over Microwave).


Skyp, Yahoo, MSN, Blueface etc are 3rd party so can't put VOIP gateway on the same network as your Broadband interface nor do QOS. Skype partially gets round this by using a proprietary adaptive codec.

If the ping to the voice gate way is over 60ms you are in trouble for Fax or Modem. Over 200ms and you will have awkwardness in phoning GSM phones or other VOIP users due to potential 400ms lag resulting in speakers interrupting each other. If you don't have port forwarding on Skype, it can have a huge delay as it has to proxy via other Skype nodes not behind firewalls. (Forward "magic Port number" in grey in Tools Connection to IP of your PC).

Solair

Hmm they must have upgraded the phonewatch alarms then since we got ours way back when it was still Telecom Phonewatch.

I don't know why they'd need high speed modems though, given that the alarm only sends about 1 line of data when it dials up.
The old Bell 103 modems would handle absolutely terrible line conditions of the type that could be generated by older switching equipment i.e. electromechanical step-by-step switches that were common place in the 60s, 70s and into the 80s.

It's not a whole lot faster than dialling codes on a touch-tone keypad

crawler

Who let all the people with big brains in here...Mods, less of this common sense approach please!!

watty

Ironically it connects to Internet As does the Yale top of range model. A 3rd party security company managages servers and calls etc for many companies including BT and Yale. I don't know if they do eircom's.

How many rural premises is internet dialup unreliable on?

I built a management system for a vending maching that used DTMF sending and receiving, it was much slower than 300baud But could also give voice prompts and expect human entered DTMF tones.

"If you are coming to restock, press 1"

There are 16 DTMF tones so it used hex to communicate with central management computer with text instead of voice. Modem was a significant extra cost in 1991

cgarvey

crawler wrote:

Who let all the people with big brains in here...Mods, less of this common sense approach please!!

Shhhhhh, don't encourage them. Besides, they were doing just fine in this little space of their own; the other threads are thankful!

cgarvey

200ms, conveniently, is at the fastest end of the ping scale of Vodafone 3G (who block common VoIP traffic).

I'd be surprised if a research & marketing spend on "Alarm/Digibox compatible" didn't generate some extra cash, given the number of digibox owners (espcially those outside of the reach of DSL, althought maybe that, too, limits them in terms of WISPs. Still though, being able to get rid of your phoneline altogether is A Good Thing (tm) for many.

Urban Weigl

I was getting stable pings close to 130ms on Vodafone 3G, before they even upgraded to HSDPA at times! And that was 3 1/2 miles away from town as the crow flies, where the nearest 3G cell is.

watty

So assuming that you could get a VOIP supplier that support T37, t38, MoIP or PCM (G.711) and the operator didn't block it, my thinking is that fax or modem over 3G / HSDPA won't work very well, if at all.

My limited understanding of 3G/HSDPA suggests that about 120ms ought to be typical, I wonder are some folks artifically delaying traffic to make VOIP unusable?