sundance-communications.com/forum Forums Other TDM Phone Systems ESI Telephones & Systems Calls being disconnected

Has anyone had this problem with the S Class 56s? When people are on the front desk phone or phones with other customers, say lines 1 and 2 and another call comes in on line 4 you hear a slight crackle and just the front desk phones that people are on calls with reset. I tried moving the co to a different port and different card, same affect. Even changed out the cabinet with same software level 4.07.18 and it does the same thing. Replaced the power supply, changed phones no change. Took voltage readings on all 7 lines and range from 70.3 to 73.4 vac. Seems low. Any ideas?

Check your system ground. Make sure the building ground is truly grounded.

All 56S class systems will have this problem sooner or later. It's a hardware issue and the cure is simple but dumb. You need to add resistance to the key telephone port lines.

Rcaman

Thank you for the reply's. I will check the grounding. How do you add resistance to the key telephone port lines?

Rcaman is probably right, I'm wrong. I've seen a similar issue but I thought it was loop length not resistance. How many ohms do you need to add?

Well....I can tell you, but then......

I have added lengths of cable (50' to 100'. ESI's fix) which is a messy and trouble prone solution. To make a neater and more manageable solution, adding between 50 and 100 ohms balanced on the tip and ring usually does it. If you are adding 50 ohms, place a 25 ohm resister on the tip side and 25 ohm resistor on the ring side in series with each lead.

Rcaman

Thank you, I'll give it a try and let you know how it worked.

TJ

Thanks Rcaman. Time to get out the soldering iron and heat shrink tubing. It's been quite a few years!

Would this also cause calls put on hold to drop ??

The 56S has a long list of things going "bump in the night." There was not enough noise suppression built into the main board and that is why the extra long cable or resistors are needed. The cables act like a crude choke. A little more elegant solution is adding resistors which dampen the noise spikes enough to keep the motherboard from having a stroke. Losing calls on hold was the first reported trouble with the 56S.

It might be a good time to let you know there are "enhanced" motherboards for the 56S which is supposed to address all the goofy issues with this system.

Rcaman