今天碰到一个错误：
no connect set and no active connection
tcp_send failed
后面回了一个 477
SIP/2.0 477 Unfortunately error on sending to next hop occurred (477/TM)
Via: SIP/2.0/TLS *.***.***.***:15081;rport=44873;branch=z9hG4bKDZ5crrXgyt10c;received=***.**.*.***
From: "+447591254371" <sip:+447591254371@sbc-**-*****.*******.***>;tag=pyvHXNpBvX3Fp
To: <sip:+86***********@**********>;tag=3a49271922ab9d30c340484dbd88012e-87d1ad84
Call-ID: 3e31829b-4040-497c-85be-d0fd482bb3e0
CSeq: 109936102 INVITE
Server: kamailio (5.8.2 (x86_64/linux))
Content-Length: 0
虽然这个问题通过别的方式进行了解决，但我还是想复现下
todo