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U2980 agent cannot hear carrier tone when performing an outbound call

Publication Date:  2017-09-29 Views:  151 Downloads:  0
Issue Description

 We have the following scenario, a U2980, IPCC, the agent is dialling out to a mobile that is switched off, however, he is not hearing the carrier message "The telephone number you have dialled is not available". Therefore, leaving the agent to wait longer and creating an incovenience for day to day operation.

Handling Process

When the agent was performing a call to a mobile number switched off, he was not receiving the carrier message that the number is not availble.

So we asked for a E2E trace to verify. From the trace we found the error message: eARF-ERRCODE-PARAM-INVALID (8285) After the CTI asked to start OCDT function.

In this case we asked the customer to verify if the OCDT is working properly by issuing the commands:


Display MSU board voice using command: DPS VOICE: MN-472, TY=STANDARD;

The customer verified and the OCDT paramerter was enabled. So we analyzed a new fresh E2E trace and we found the following:

1. From the outgoing agent calls U2980 -> Carrier, we were receiving a progress message, but the gateway can only play voice when receiving an ALERTING message.

Therefore, there are 2 ways to have the carrier message played:

1. Request to the carrier to send an ALERTING message to the U2980.

2. Modify PRA Tunk configuration with the following parameter of control: SVRCTRL.

The MML command should be: MOD PRATG:TG=23,SVRCTRL=SVR1-1;

Root Cause

The soft parameter SVRCTRL was not enabled.


Enable the soft parameter SVRCTRL for all the PRA trunks.

The MML command should be: MOD PRATG:TG=23,SVRCTRL=SVR1-1;