Unable to authenticate phone

[thumpurr]

I got a note 4 as an upgrade and it worked briefly and now I cannot make any calls, and all incoming calls go to voicemail.  I keep getting we are sorry unable to authenticate phone and then it tells me to dial #8899, which sends me through automated options none of which apply to the problem I am having.   I am able to text and get on Internet but cannot make calls.  Is there a number I can call to talk to a physical person, or another option to address this problem?  Thanks.

[Snn5]

Customer Service

(800) 922-0204