flow:
  - start|REPLY_ROUTE_NAT:
  - exit|REPLY_ROUTE_NAT:
sip_in:
  - '^SIP/2.0 180 Ringing'
  - 'CSeq: 2 INVITE'
sip_out:
  - [
      '^SIP/2.0 180 Ringing',
      'CSeq: 2 INVITE',
    ]