[May 1 05:12:14] DEBUG[7932]: chan_sip.c:26041 handle_request_do: Invalid SIP message - rejected , no callid, len 448
Seems like You are using Asterisk, so the 401 is a normal response when you are trying to do a call, then the phone need to respond with the ACK and another INVITE with the result of the challenge in order to allow the call.
About the other message:[May 1 05:12:14] DEBUG[7932]: chan_sip.c:26041 handle_request_do: Invalid SIP message - rejected , no callid, len 448Seems like Asterisk(or maybe a route issue) lost or destroyed the callid and cant send the other SIP messages.