SPA112 fax settings with 1 line or 2

[canyouhearme]

1st, this is probably the hardest forum to find (on Cisco's support site) that I've ever encountered.  Like they're trying to keep it a secret.

Not sure WHY they have this under (only) Small Business - but I found it!  Not under any forum menus, but by searching term "SPA112."

If trying to fax over VOIP, having 2 lines set up w/ your provider is probably always preferrable.  But, it you only have 1 line, there are many suggested faxing optimization settings in the Admin Guide for SPA 100 series.

Question: If one had only 1 line, would making the changes for faxing suggested in the SPA112 Admin. Guide likely cause problems - or not - for voice transmission, if the fax settings were left in place? 

Or with only 1 line, would you most likely have to change settings to get optimum fax results, then change them back for voice use?

Thanks.

[nseto]

Most of the time, you'd have problems with faxing, so you'll want to optimize for fax.  You'd just be limiting your voice options like removing call waiting and 3 way calling.

[canyouhearme]

Thanks.  I'm not sure that answers my question (if there is "an" answer).

Optimizing for fax doesn't tell me whether it may / may not hurt voice quality, aside from losing some features - as you mention.

1st, I don't know if software faxing (vs machine) w/ an ATA supporting T.38 works reasonably well, or if it's barely better than before T.38 came out. 

Because of the reported problems SPA112 has w/ caller ID, a friend /w more VOIP experience recommended I look at a different brand.  One suggested only has 1 phone port.  I think (hope) Cisco will release firmware that resolves some of the current problems.  I really don't think I'd want to buy a 1 phone port ATA or have only one active SIP, unless configuring for optimum faxing would NOT hurt voice or lose important features (like call waiting).

I may not be able to get a 2nd SIP w/o paying a good deal extra.  Reconfiguring ONE setting (i.e., call waiting) back & forth wouldn't be bad for me.  But, reconfiguring several settings to fax (not often), then back

would be a pain.  If optimized fax settings also hurt voice quality, then leaving one line optimized for fax isn't an option.

[Sage Major]

I use these lots for faxes.  The only change from the default config related to faxes that we use is this one.

FAX Disable ECAN: yes

I have thousands of these deployed and they work well for most data calls.  Issues mainly come up with old smog machines.

If we know its only a fax line we also set

Preferred Codec:    711u Use Pref Codec Only:  yes Echo Canc Enable:   no

[canyouhearme]

Thanks.  If I understand, sounds like wouldn't be best (for voice) to leave it configured w/ fax / data settings - all the time.  Or have 2 lines - 1 for fax & 1 for voice, as was my guess.

By "work well for most data calls," does that include SOFTWARE faxing?

W/ PAP2T, working w/ my VOIP support, suggestions on DSLR, never could get software faxes to go.  That was before T.38.

What is a smog machine?

[Sage Major]

I did not explain myself well.  Faxes and voice work well with the default settings, for us by just making that one change.

Alarm lines, elevator lines, credit cards all work.  Now I am both the phone company and ISP so the data is all on-net with qos 100% of the way, but even off net customers plugged in bheind some random isp work most of the time.

Smog machines are use in auto repair in California to do emissions testing.  They are all really old and about 30% of our customers with those require us to run a pots line.

As for software faxing, I know of only one customer who does it and they had a really old modem and did have issues with it, but that was on a pap2t

[almiller]

Hi Sage and the rest,

Pardon me for jumping in -  sounds like I am trying to do something similar.  Send a fax using a fax machine connected with a SPA112 to a SIP trunk (Vitelity).  I spoke to a guy I know that is using this configuration and he says it works great. 

I am trying to send a fax outbound.  I hear the phone dial, it gets answered by remote system, then I can hear the fax tones but they never really lock on or get fully engaged. Is there anything specific I can do to trouble shoot this?

Allen

[Anthelme_Kolbe]

Set Jitter to "very high", set jitter auto adjust to "disable", turn off 3way, call waiting etc, and i'd suggest it would be a royal pain to keep changing them but you can do this via the http admin menu built into the device. which would save buiding a config file and rebooting it each time.

Also i would suggest disabling ECM or forcing the fax to connect at 14.4 or lower.

A

[Sage Major]

Make sure you have all the echo cans turned off and that g711 is set at the first codec

You can also look at the sip messages to see if they are using 711

[terryip83]

Erwin,

Have you updated the ATA firmware to the latest release? I have found that the fax with T38 appears to be a bit more reliable on 1.3.1.

[erwindelisse]

I have a SIP account with T38, with above settings it doesn't work. When I have a SIP account without T38 it will work perfect. What can I do, by the account with T38?

Who cabn help me!

[joelblack1]

These settings worked great for fax!

Have you ever come up with a solution for using an ATA with smog machines? Or is the answer just "use a POTS line."?

[Dan Lukes]

I assume you are asking for modem (data) communication.

Up to 9600Bd (or 14400Bd with V.32bis and high quality Internet connection) it should work with the settings similar to fax (with no T.38 support).

If yours device is using V.34 or newer, speeds above 14400 or your Internet line is not so good quality, you may be limited to "use a POTS line" approach.

[terryip83]

The main issue I've seen when testing these with a voice call on a line with optimal fax settings applied is that you do get a bit of echo depending on handsets used at either end. I've had these working quite well with T38 enabled for fax.

An unforseen bugbear I've had is that if you have both lines enabled for T38 and one line is use mainly for voice is that the voice line will try and renegotiate with T38 if the handset hears the fax tones from the fax machine. You then end up with a call where neither party can hear each other when G711 is reapplied.

[canyouhearme]

Sage major, terryip83 - for faxing software & VOIP, doesn't sound like the long awaited T38 protocol was a cure all.  Maybe better results using fax machines.  I realize POTS & VOIP are different technologies, but software faxing over POTS worked great for me.

I'm not running a business, but at least w/ SPA112, doesn't sound like using fax machines & voice w/ VOIP (2 lines) is perfected.  Don't know about trading in my printer (w/o fax) for one w/ fax, just yet.  Not until I'm fairly sure the 2 VOIP lines - 1 voice, 1 fax configured - both work fairly well w/o interferring w/ each other.