sundance-communications.com/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's Loud Dial Tone from Adtran TA850 Channel Bank

I'm experiencing some weird behavior from an Adtran Total Access 850 channel bank. The network port of the TA850 is connected to a Sangoma T1 card in an Asterisk PBX. The channel bank has 6 FXS cards that service 24 analog extensions. Timing on the T1 circuit between the channel bank and the server is provided by the Sangoma T1 card.

I have run into a situation just recently where one or two of the analog extensions can't dial out. They get dial tone, but the dial tone doesn't stop when an agent starts dialing. The call won't connect and the agent still hears dial tone. This just started happening two days ago after working without problems for about a month.

I first tried power cycling the channel bank. After the power cycle all 24 extensions had a very loud distorted dialtone. Multiple power cycling and still the loud dialtone. And, the affected extension still couldn't dial out.

The loud dial tone was restored to a normal dialtone after I restarted the asterisk server and re-power cycled the channel bank. I've had to do this twice now.

Does anyone have an idea as to what might be causing the dial tone problem? I'm new to this telecom stuff, and I'm not familiar with all the ins and outs of this stuff, so any help would be much appreciated.

Do you have the channels properly programming...loop start, ground start..etc.

You didn't say that whether those 2 extensions were finally able to dial out. If not, don't forget that DTMF dial pads can go bad. Look for the simple stuff first. Try another phone on the effected extensions. If NO extension can dial on a SPECIFIC channel, it can be a telco trouble. Remember, someplace those channels break back down to analog to read the DTMF tones. The DTMF doesn't get read and encoded at your end, that happens where it changes back to analog voice. John C. (Not Garand)

First, thanks for the replies.

Lightninghorse: After resetting the Asterisk server the extensions can dial out. The annoyingly loud dial tone is also gone. As far as it being a TELCO problem, the TELCO isn't involved in my connection from Asterisk box to the channel bank. The only T1 circuit is the one between the channel bank and my asterisk box. So, DTMF for these extensions (if I am correct) comes from Asterisk, which is only about 5 feet away from the channel bank.

FYI, once the agent dials from the extension, it hits my Asterisk box and is then forwarded via a SIP trunk over a dedicated fiber network to my long distance provider. It's a pretty slick solution. Killer long distance rates too. But, I'm sure my problem is local.

anthonyh: I checked the channel programming on the channel bank and on my Asterisk server. All 24 channels are the same. All 24 FXS channels are configured as Loop Start. Asterisk, as well as the Sangoma drivers for the T1 card, are configured for FXS Loop Start too. (Just in case you ask, I did use FXO signaling for the FXS channels in Asterisk like I'm supposed to.)

Thanks again.