Eternal call transfer recalling back to operator

[bigglesnz11]

I have a customer running a TDE 100, They appear to have an issue ( have not been able to replicate) apparently after an incoming call is transferred off site (CO to CO transfer) after 1 minute the call is disconnected from the transferred call and the original call is pulled back to the operator. From what I understand , the call shouldn't come back as the call has been established end to end.
COS allows CO-CO transfer and trg group time limit I sst to 600 seconds

Any ideas?

Cheers

 

[obtsystems]

Do they have the enhanced licence and disa supervision on the system.

If not the system can not take a call back. Could be if a call comes in and is transferred to a external phone by someone without class of service permission to do so it will bounce back