Analog TNs held off-hook with modems attached

[mjgolli]

Here is an interesting thing that I have been dealing with for quite some time...

I have an Opt 11c. I have two modems, USR external 56k hardware modems...one on TN 19 0 and one on TN 27 1. These modems are connected to a computer that uses them to dial out to get status from vending machines at outlying locations. (bus pass sales kiosks) The two modems also receive incoming calls from the vending machines to report problems.

There are four remote machines on regular telco POTS, and two machines at the location of the phone switch. These are on TN 20 11 and TN 20 8, respectively.

The computer at the phone switch dials the outlying machines via 7 digits, and the internal machines via 4 digit extens. All of the TNs above are assigned DIDs.

The problem that I am having with them is the two modems attached to the central computer will work fine for a while but will eventually get to the point where it will hold the line off-hook. It will happen with either one or both. The amount of time it takes to get to that point is seemingly random. In the switch, the affected TN(s) will return a STAT of busy. The problem is fixed by LD 11 DISU both modem ports, turn the modems off and on, then LD 11 ENLU both ports. It does not seem to matter what vending machine the modems dial.

This problem only happens with these two modems. The two modems in the local vending machines work fine. We have modems on other station around for bank transfers, remote dialup, etc. that all work just fine.

The vendor of the vending machines says that it must be our phone switch causing the problem. I am not so sure.

Here is the setup for one of the modem lines...

DES  F5V7B 
TN   027 0 00 01 
TYPE 500 
CDEN 4D
CUST 0 
WRLS NO
DN   8333 0     MARP
     CPND 
       NAME GFI Vending Controller 2
       XPLN 27 
       DISPLAY_FMT FIRST,LAST
AST  NO  
IAPG 0 
HUNT 
TGAR 1 
LDN  NO
NCOS 3 
SGRP 0 
RNPG 0 
XLST 
SCI  0 
SCPW 
CLS  CTD DTN FBD XFR WTA THFD FND HTD ONS 
     LPR XRD AGRD CWD SWD MWD RMMD SMWD LPD XHD SLKD CCSD LND TVD 
     CFTD SFD MRD C6D CNIA CLBD AUTU
     ICDD CDMD LLCN EHTD MCTD 
     GPUD DPUD CFXD ARHD OVDD AGTD CLTD LDTD ASCD 
     MBXD CPFA CPTA DDGA NAMA MIND 
     MCRD 
     EXR0 SHL ABDD CFHD DNDY DNO3 
     CWND USMD USRD BNRD OCBD RTDD RBDD RBHD FAXD CNUD CNAD PGND FTTC 
PLEV 02 
AACS NO
MLWU_LANG 0

The other modem lines, both its partner and the local vending machines, are exact duplicates.

Is there anything obvious in the setup, above, that I should change or may be related to this problem? Is there something that I should add?

I would really like to eliminate the phone switch as the problem...or, if it is the problem, fix it.

Thanks!
Mike

 

[johnpoole]

i use cls xfa and ftr phd.. seems to help.. the modem init string can be adjusted

john poole
bellsouth business
columbia,sc

 

[pbxn]

You may also want to add ldta in the class of service.

 

[johnpoole]

line disconnect tone allowed.. could help, i may add that to some of these 1940 style dictaphones..

john poole
bellsouth business
columbia,sc

 

[mjgolli]

Thanks for the input. I have applied the changes to the affected TNs, so we shall see...

Mike

 

[TDMtek]

If the Analog TN’s are not in lockout you may be able to “Trace” the call from LD-80 and tell if it was a out-going or a incoming call with the called number or CLID, that would help in determining if it’s a Port/TN issue or a remote modem issue.
My two cents worth is it’s not the TN’s because you stated none of the other modems in the system are having disconnecting issues.