===== test_crcx =====
composed:
-----
CRCX 1 17@mgw MGCP 1.0
C: 2a
L: p:20, a:AMR, nt:IN
M: loopback

-----
composed response:
-----
200 1 OK
I: 1

v=0
o=- 1 23 IN IP4 10.9.1.120
s=-
c=IN IP4 10.9.1.120
t=0 0
m=audio 16002 RTP/AVP 98
a=rtpmap:98 AMR/8000
a=ptime:20

-----
response cb received:
  head.response_code = 200
  head.trans_id = 1
  head.comment = OK
  audio_port = 16002
Done