Analog Lines Not Hitting AA

[tech.trey]

I have a NEC 9100 installed with analog lines. The provider is using an Adtran total access 900E to provide the analog handoff from their fiber network. I am having an intermittent problem of when you call in the AA does not pickup. The line appearance on the phone will show busy when line at D-marc is not. For example when problem occurs line 2 will show busy on NEC phone, however line 2 will be free on test set a D-marc. When this occurs you call the main number and the AA does not pickup.



I have done a "line balancing" per request of NEC and made some changes to the transmit and receive gsin levels.


Has anyone ever encountered this issue? If so have you found a solution?

 

[meyer1y2k]

One idea that comes to mind is to make sure the analog trunk ports on the 900E are providing loop disconnect.

To test this, isolate from system. Place your test set on a line. Call from another phone like your cell phone. Answer. Hang up cell phone and listen. If you hear a distinct double click then you are getting loop current disconnect. The current drops for about .5 seconds and is then re-applied, signaling to the phone system the call is done.

If the line goes straight to dial tone or busy signal with no click you are not getting loop current disconnect.

This problem appears intermittent because if the call has been answered from a station on the NEC, both sides will hang up, dropping the line. If a caller leaves a voice mail and hangs up, the system does not disconnect because it has not received a positive disconnect. This condition could also occur if the outside caller hangs up before anybody/anything answers.

This is the most common cause of your trouble when behind any type of gateway and should be eliminated first.

 

[OzzieGeorge]

Sorry but there is a fundamental fallacy here. If the PBX isn't actually releasing the lines, the lines should appear busy to incoming calls as they would still be looped by the system. You could try checking 14-02-18 for each line but IMHO that is a long shot!

 

[meyer1y2k]

What I have observed first hand is the provider will release on the trunk side but the PBX, not receiving any positive disconnect, continues to show the line in use. This results in the ring no answer. The phones won't ring and the AA will never answer. A system or card reset clears this temporarily but the permanent solution, if this is the cause, is to make sure your provider is providing loop disconnect. Never hurts to check and can save hours of troubleshooting. 14-02-18 looks like a good idea if the line gets to a point where a reorder is busy signal is given and the provider will not cooperate.

Another fun fact is that older Adtran gateways were not set to provide loop disconnect on FXS ports. We would always fight with providers that installed these and would not enable it until there was a vendor meet. I am not sure if the default is different on the 900 series.

 

[belevedere]

Have your provider switch them to ground start. Reprogram your lines to ground start.

 

[erniejoey]

Happens with FIOS as well. We have to either reset the blade or reset the system. We program the Time Out on the DAT to Hang Up. Hope that helps...

 

[meyer1y2k]

The ground start post is an excellent one. If this can be done, and the provider will do it, there needs to be a ground either on the Adtran or the NEC to provide the short to ground on the tip side to start dial tone when calling out (which is why they are called ground start trunks). You also have to keep in mind that GS trunks are polarity sensitive. If you find you can receive calls but not make calls, figure out which trunks, and reverse the polarity. You sometimes run into this when there has been repair work and the polarity was not properly observed. Ground start trunks also never "glare" meaning you accidentally pick up a line that just started ringing in.