atcomsystems.ca/forum Forums TDM Business Telephone Systems NEC Telephones & Systems SV8100 - Analog Trunk hang if incoming call is transfered to Voicemail

Our customer SV8100 system has Auto Attendant for Analog Trunks and Voice Mails for all users. And we have problem that the analog trunks don't release although the outside caller already hang up after reaching to voice mail.
Scenarios:
- Make incoming call to system and reach to VRS
- Dial extension after hearing Greeting message
- After 3 rings no answer, incoming call is transferred to voice mail
- Caller hang up call
- That trunk is hang
I have to physical unplug analog trunk to release the call.
Is there anybody have faced to this issue before?
There is no problem if no voice mail transfer.

If they abandon the call while the VM is playing the greeting and options, then it will hold the call until it is played out and transferred to the "press no key" destination.
This sounds like you have loop start lines. If so, then convert to loop start trunks (disconnect is provided) or better still, ground start lines (positive disconnect provided).

All trunks are loop start as default setting.
Should I change to ground start to solve the problem (PRG 14-02-14)?
I tried to activate Busy Tone Detection (PRG14-02-09) and Detect Network Disconnect Signal (PRg14-02-12) but the problem is still there.

If you want to change to ground start, you first need to place the order with your telco provider.

You are not getting a disconnect signal from your carrier (they should be sending it). I haven't placed an order for ground start lines in 15 years but it will give you the supervision.

Test your lines for the proper disconnect signal.

If they switch to Ground start you will not get caller ID

Make sure you have supervision turned on,. The timer may be off as well. Contact the telco and find out what the disconnect time is. Every now and then I run across this.
Also you can assign a code and COS to disconnect the line.

Our country Busy Tone Specification is 500ms ON/500ms OFF, 480Hz
I found out 1 doc and followed below configuration. It's OK now:
PRG 14-02-09: Busy tone detection: 1
PRG 14-02-18: Busy tone detection on talking: 1
PRG 14-02-19: Busy Tone detection frequency 3 (3 times)
PRG 14-02-20: Interval: 10 (1000ms)
PRG 80-04-06: 14
PRG 80-04-07: 17
PRG 80-04-08: 14
PRG 80-04-09: 17
PRG 80-04-12: 1
PRG 80-07: table 1: 48(480Hz)

Must configure all the items, It will not work if there is any missing command.

Busy tone disconnect has to be setup fairly precisely as November says and will depend that tone cadence is supplied from the central office when the trunk disconnects . Here in New Zealand we generally use reorder tone 250ms on / off on trunk disconnect so our defaults in PRG 80.04 reflect that.