W52P - Extension Dialing Issues

[adam.comws]

Good day,

My office set up is as follows:

ADSL Router into PoE switch.
2 x W52P Base stations into PoE switch.
1 x T48G into PoE switch.

All phones are DHCP.

It is a Cloud PBX.
All extensions are registered and we are able to make calls and receive calls.

When we dial an extension from any extension, it will ring at both parties, but when party 2 answers, it wont stop ringing in the ear of party 1.
Party 2 display will show the call is connected, but party 1 will showing it is still ringing.

We have registered the extensions on softphones and it tested perfect.
We have tried many firmware versions, but this hasnt worked.

Any suggestions: