Symptoms
Microsoft Skype for Business 2015 (Lync 2013) accounts that are configured to support media bypass cannot resume an incoming call from a public switched telephone network (PSTN) gateway after they put that call on hold.
Resolution
To fix this issue, install the December 6, 2016, update (KB3127976) for Skype for Business 2015 (Lync 2013).Note Lync 2013 was upgraded to Skype for Business in April 2015.
