We are currently operating a Lync 2013 environment and utilize Spectralink 6000 DECT servers at our sites for individuals who are away from their desks. An issue that we have discovered is that if User A is on a DECT phone calling User B who has both a DECT phone and simultaneous ring enabled (pointing towards his mobile phone), the following happens:

1. If User B answers on his cell phone, the call is fine

2. If User B answers on the DECT phone there is no audio for User B

If simultaneous ring is not enabled DECT to DECT calls are fine.

I have pulled call logs and as far as Lync is concerned the calls are completing the way they should.  I have compared the configurations on this DECT server to other DECT servers and the settings are identical.

Any thoughts?

That is correct.

I have been unable to replicate this problem in house, I will contact my site contact and see what he says.

Thank you for the response.

I presume the call is being forked by the DECT server is this correct?

what happens if we test with Lync client?

Hi,

From the link below, Spectralink 6000 phone is not in the list as the Lync Server 2013 certified IP Phone, even the Lync Server 2013 certified IP Phone for Spectralink, only Spectralink 84-Series Wireless Telephones support Simultaneous Ring:

http://partnersolutions.skypeforbusiness.com/solutionscatalog/ip-phones

Best Regards,
Eason Huang

According to the local contact, using the Aastra phone and the client react normally with the simultaneous ring enabled and a DECT phone associated with the account. 

Contact Dect if the they are forking the call