MCC 7500 Headset Audio Delay

[KR899]

Hello,
We have an issue with headset arbitration between our telephones and the MCC 7500. The telephone connects to the VPM and the headset is plugged into the headset jacks, also from the VPM. Whenever we receive a call, there is a delay in audio of approx. 8-10 seconds. The dispatcher cannot hear the caller and vice versa. If I disconnect the phone from the VPM, there is no delay. If I close the radio app, on the Motorola console, the delay goes away. Also, the volume on the headset jack does not work for the phones but works for the radios. Thus the "our stuff works".

I was told by our radio support staff that there is nothing to configure, in the Motorola software or the VPM, that could create/fix this issue. I'm being told its not their issue, that it is something with the phones. I'm not a radio guy and I'm not allowed to touch the radio system so I'm stuck.

Are there settings for the headset arbitration? Has anyone heard (or in my case, heard after 10 seconds) of this issue?

Thank you!

 

[jeepsandradios]

What phone system do you use and whats the arbitration box ?

Most have TX/RX audio and Off Hook. The VPM is looking for Off Hook and at that point should send audio to the headset jack if incorporated via the manuals. Any decent radio tech should be able to test this feature with a Tims set and a MODAPT with a jumper wire. Send audio into TX (to VPM). With the Off Hook not gorunded you should hear radio and as soon as the off hook is grounded you should here tone from the TIMS set. If that works then it is an arbitration issue of the phone system. Similar test could be accomplished via arbitration. Tims should hear audio from phone system and see a closure as soon as you pickup from the phone system.

In the end it appears the off hook is your delay on one side or the other.

Not knowing who is servicing the equipment it appears little real diagnosis was done.

 

[kf8yk]

Also,

Make sure the phone system is not asserting external jack sense (pins 1 & 2). if ext jack sense is active the VPM will ignore the off hook signal.

The VPM expects dry contacts from the phone, verify the phone is not providing a logic voltage.

 

[KR899]

What phone system do you use and whats the arbitration box ?

Most have TX/RX audio and Off Hook. The VPM is looking for Off Hook and at that point should send audio to the headset jack if incorporated via the manuals. Any decent radio tech should be able to test this feature with a Tims set and a MODAPT with a jumper wire. Send audio into TX (to VPM). With the Off Hook not gorunded you should hear radio and as soon as the off hook is grounded you should here tone from the TIMS set. If that works then it is an arbitration issue of the phone system. Similar test could be accomplished via arbitration. Tims should hear audio from phone system and see a closure as soon as you pickup from the phone system.

In the end it appears the off hook is your delay on one side or the other.

Not knowing who is servicing the equipment it appears little real diagnosis was done.

Thank you. We are using a Cisco VOIP telephone that connects, via a combo proprietary cable, to an Ultratec InteleModem. I have attached a drawing.

 

[kf8yk]

You should include the 911 workstation vendor name too. A search for the Ultratec Intellimodem just returns with a old TDD/TTY modem.

The Cisco 8851 does not have any off hook relay functionality. It does support Cisco electronic hook switch (EHS) which can provide off hook status to a compatible headset or accessory. EHS uses a serial data protocol to convey hook state & is not compatible with radio consoles like the MCC series.

Most E911 workstations include some type of external relay/audio box that connects to the workstation PC and among other functions provides the off hook relay. Any 911 workstation that conforms to the NENA standard should have a suitable Radio/Telephone Headset Interface available, see section 3.10 in the standard.

 

[KR899]

The vendor is SPOK, previously known as AMCOM. The Intellimodem is an old TDD modem. This is the only device that sits in between the phone and the VPM. The vendor has stated this configuration has worked previously at other Cisco VOIP agencies.

 

[Tech21]

Set your phone system to allow 3rd party arbitration to be controlled by the radio.

 

[jeepsandradios]

Again proper testing needs to happen. I've installed 100's of aribtrations to VPM's and never seen that issue. It appears to be a module issue on the phone side. Until a proper test is completed no one here can fix your issue. Get your ST and phone vendor on site to resolve. There are boxes that just dont support what your trying to do.

 

[KR899]

I know I need local assistance. My goal in asking the forum was to understand what needs to be looked at as I have obviously not received the right level of support up to this point.

Thank you for everyone's assistance.

 

[jeepsandradios]

As said its all in the interface. Its a total of 6 wires. TX Audio, RX Audio, Ground and Off Hook. Any competent technician should be able to open the manual and look this info up.

Pin Number Description (+) and (–) symbols indicate pin polarity
1 Jack Sense In (–)
2 Jack Sense In (+)
3 Audio In from Phone System (–)
4 Audio Out to Phone System (–)
5 Audio Out to Phone System (+)
6 Audio In from Phone System (+)
7 Off Hook In (+)
8 Off Hook In (–)