general telephony question 1

[pmcilnay]

I'm a tech for an ILEC, but this has me stumped. 2-line hunt group, 2-line phone. If you placed line 1 on hold, access line 2, incoming or outgoing, after about 25 seconds line 1 will drop. Cust. changed out phone. I'm 200 miles away, but I'm trying to find out how the telco is delivering dial tone (ip, carrier or pots). Any ideas?

 

[PERRYPJ]

As long as there is a incoming call there and you press Hold it should stay on Hold till you go back to it. What you have sounds like the phone is not placing the call on Hold, all Hold is a short across Tip and Ring to hold the call up. The phone may look like it is on Hold but most likely it isn't.

OLD ROLMEN WORKING ON NORTELS AND AVAYA

 

[pmcilnay]

I agree with you, but the customer switched out the phone with another and is getting the same results. I also found out that the telco is a cable company, likely sending on coax. I don't know how this converts to pots (ip or similar to a channel bank, carrier). My thought is to have the telco monitor the line to see where the diconnect is coming from.

 

[ISDNman]

1) With the call on hold what is the loop current?

If it is below 24 mA that could be the problem. Phone are supposed to have a 600 resistor for hold not a dead short.


2) ANy chance in addition to being a hunt group the is call waiting on the first line. If there were an open switching interval (AKA flash) when the call waiting is activated that could cause the phone to clear the call.

Good luck.

PS - did the customer try a different phone of the same type, or a completely different phone? The phone may not be broken but simply badly designed.

If you ask a better question you will get a better reply. Be specific so we can help!

 

[TouchToneTommy]

Are they actually CALLING someone on Line 1 and putting that on hold? Or are they just going off hook, getting dial tone, and putting THAT on hold?

If you put dial tone on hold, don't dial anything, when the dial tone timer expires, the telco will send an open loop disconnect, which will drop the line on hold.

Have them dial something like the milliwatt test tone, put that on hold, and then go the line 2 to make some other call, and see if Line 1 stays on hold.

 

[ISDNman]

TTT

Excellent points.

PMC

You are correct, if they monitor the line the disconnect cause value and location would be useful.

These "Analog Terminal Adapters" used for VOIP and cable are frequently of dubious design. Definitely see if you can find a way to measure the loop current on hold.

Best of luck

If you ask a better question you will get a better reply. Be specific so we can help!

 

[donb01]

I am wondering if this is all happening on cable (VOIP?) and the service is spotty, would a call on hold be more likely to be dropped if there was a service glitch than an active call? My thought is the active call is actively sending data back and forth and an interruption in service may just trip some kind of packet-retry timer, where the call on hold isn't really doing anything and would be more likely to lose sync and drop?

I may be way off base here, but sometimes a good brainstorm gives other ideas! I guess I would also toss in another vote for the guy who asked about call waiting. I've never given much thought to what happens if a call is on hold when the "dropout" for call waiting comes across...

 

[Lundah]

Whatever the 2-line phone is doing to keep the first line on hold is the likely culprit here. Could be something as simple as reversed polarity on line 1, and the phone isn't robust enough to handle it.

 

[oldtimerbob]

You don't say anything about how the cable company has the phone lines hooked up at the site. VOIP will need have a way to see the second line (phone number) at the user end from the hunt group,normally an ATA is used.
From that point you can use your analog 2 line phone if the jacks area wired correctly depending upon whether the phone needs a seperate connecton for each line or can get it off of one cable from the phone to the jack.

Bottom line:
Have the cable company send a tech out and solve the problem and be sure your end user is using the correct phones to match the set up.

Good Luck

Has been in the cabling business for about twenty years and is now the Sr PM for a cabling company located in the Los Angeles area.

http://www.globusinc.net

Also a General Class Amatuer Radio Operator.

 

[nascomm1]

Another thing to look for, is there any old abandoned 1A key equipment still on the lines, I had a similar problem a few years back at a business that installed 4 line phones in place of their old 1A2, but the Embarq tech only cut the ends off of the old amphenol cables and installed two rj14s at each station and left the 400 cards in the loop.