Double Tones on Conference Lines

**MarkTomlinson** · 10-25-2010 08:12 PM

This is a weird one. So I thought I'd start with the forum in order to see if other people have this issue occasionally, rather than taking it straight to a service ticket.

New VOIPo user, although not new to VoIP. I use my VOIPo line on my work-from-home days and start or join lots of conference calls as well as check my corporate voice mail. When I want to join or start a conference call, I have to enter a ten digit pass code. Often (I've noticed it most in the morning, but often in the afternoon as well) the conference line rejects the number I entered even though I KNOW I entered it correctly. When it reads the number back to me, there are often duplicates. For instance, I enter '1234567890' and the conference line says, "The number you entered, 1 2 2 3 4 5 6 6 7 7 8 9 0, is not a valid pass code".

The problem goes away after four to six tries. (The conference line hangs up on me after two failed attempts, so I end up calling back two or three times). And then the problem goes away for most of the rest of the day. Oddly, it seems to occur after I have not used the phone for a couple of hours - but that's kind of speculation based on hindsight.

It's not the conference service - we use Conference Plus and if this was a common problem they'd be out of business. It's not my phone - I usually use the cheap Uniden cordless, but I've been able to recreate the problem on our better quality Panasonic. Besides, as I alluded to above, I never had this issue when the Uniden was attached to the cable-line. I'm a tech guy who works with other geeks, so we've practically all got VoIP and I'm the only one having this problem. I don't recall having this problem with our voice-mail, but admittedly the longest string of numbers I enter there are my four digit extension and pin. And I've never had this problem with land-lines, cable-lines, or previous VoIP (a couple of years ago).

All this seems to point to the VOIPo provided Linksys RT31P2, my Linksys WRT160Nv3 running DD-WRT, or VOIPo. (By the way, same issue with or without QoS on the router).

Thoughts? Suggestions?

**Hawkmeister** · 10-25-2010 09:26 PM

I'm in the same boat as you with the work-at-home conference lines. I feel your pain and have experienced a 'similar' symptom (it misses the key instead of 'double toning'). However, I found a fix.

My provider gives me the option of using a toll or toll-free (800) number to access the service. When using the toll number and entering the pin code, it will miss one or two of the keys pressed. When I use the toll-free, it works 100% of the time.

I had placed a ticket with support. But, they felt it was the conference line provider's issue.

My setup is WRT54GS running dd-wrt v24-13064_VINT_mini, PAP2T behind router. All VOIPO router recommendations set.

**MarkTomlinson** · 10-25-2010 11:30 PM

I use an 877 number all the time, I guess I could try a local number. Either way, I suspect the conference line is just sensitive. But sensitive to what? If this was a problem on their end, I'm sure they would have it resolved by now. It must be hearing double tones (or none in your case), so where is the problem originating?

I'm leaning toward thinking it is the VOIPo server I connect to, although I wouldn't immediately rule out DD-WRT. More research required!

**holmes4** · 10-26-2010 08:15 AM

Interesting. I have used Voipo to place dozens of conference calls where I have to key in the numbers, and have never had a problem with doubled digits. I think maybe once I had an issue with it not recognizing the numbers and when I redialed, it was ok. Sometimes I use a toll-free number, sometimes not.

**stevech** · 10-26-2010 09:47 PM

I used to have a Linksys PAP2 ATA used with ViaTalk (Asterisk), not VoIPo. It garbled touch-tones received badly. I could call another landline and push DTMFs - they were badly clipped and distorted. As a result, most but not all IVRs (voice mails, conference bridges, bank logins, pharmacy prescription refills) failed. Not the analog phone's problem- tried many. All work OK on a POTS line. Tried changing to SIP signaling from the ATA but that didn't work because of VoIP service provider SS7 bugs.

None so far with this VoIPo ATA from Grandstream.

**MarkTomlinson** · 11-01-2010 07:28 PM

Well, a week later and the problem persists. I guess I get to open up a ticket.

But here's the weirdest part; I decided I'd record it happening so that I had something to show Tech Support. But every time I entered *28 and the phone number, it worked! Twelve times at two different times of day, if I dialed *28877xxxxxxx and then the conference code it worked every time. I alternated that with just dialing 877xxxxxxx and the conference code to ensure I was still having the problem.

So why is it that dialing the number directly creates questionable tones that the conference line sporadically interprets as double tones, but dialing with *28 in front does not?

I guess I'll open a ticket and find out.

**stevech** · 11-01-2010 08:07 PM

Maybe due to routing that any given call takes, even to the same number?

**MarkTomlinson** · 11-02-2010 10:27 PM

Originally Posted by stevech

Maybe due to routing that any given call takes, even to the same number?

Something like that, I think. Try dialing *28 and then wait a moment. I get a second dial tone with higher pitch. This leads me to believe the call is going through a second ATA (or something to that effect) which interprets the tones correctly from my ATA and then passes on higher quality tones.

Because of the above, and since I seem to be the only one having this problem, I believe it is the Linksys RT31P2.

I've opened a ticket and will let everyone know how it turns out. That way if anyone else experiences something similar, they can point Tech Support here.

**tritch** · 11-02-2010 11:55 PM

The call routing is different for *28 calls as stated in vPanel:

Note: This feature is intended for occasional use only. When you record a call, the audio for the call is routed through our Call Recording server instead of our primary media gateways and as a result call quality may be reduced.

**MarkTomlinson** · 11-03-2010 03:11 PM

Originally Posted by tritch

The call routing is different for *28 calls as stated in vPanel:

Note: This feature is intended for occasional use only. When you record a call, the audio for the call is routed through our Call Recording server instead of our primary media gateways and as a result call quality may be reduced.

Yep. That was it. Got the following reply to my ticket;
"Please try to call into the conference again. I've updated your DTMF method and have moved you to a closer server."

Problem is gone! As an added bonus, I was perfectly fine with my call quality but now it's even better. Talked to my boss for about half an hour and kept thinking, "Man, this is clear".