when ever i make call using demo project provided by Ring central to make a voice call.

the receiver device gets the call , it rings but gets disconnected after 2 secs automatically.

and i get error

Wed Sep 19 2018 19:14:53 GMT+0530 (India Standard Time) | sip.transport | received Web Socket text message:

SIP/2.0 500 Internal Server Error

Via: SIP/2.0/WSS qclr3m3j2mrg.invalid;rport=31606;received=10.48.20.10;branch=z9hG4bK9756497

From: <sip:18882199988*101@sip.ringcentral.com>;tag=7jjrsp8b2j

To: <sip:+919574636432@sip.ringcentral.com>;tag=gK00934b08

Call-ID: bv9oo63dnsn4akt209ef

CSeq: 5461 INVITE

Content-Length: 0

so want to know why am i getting this error.