def send_answer(opts = {})
      opts[:retrans] ||= DEFAULT_RETRANS
      msg = <<-MSG

SIP/2.0 200 Ok
[last_Via:]
From: <sip:[$remote_addr]>;tag=[$remote_tag]
To: <sip:[$local_addr]>;tag=[call_number]
[last_Call-ID:]
[last_CSeq:]
Server: #{USER_AGENT}
Contact: <sip:[$local_addr];transport=[transport]>
Content-Type: application/sdp
[routes]
Content-Length: [len]

v=0
o=user1 53655765 2353687637 IN IP[local_ip_type] #{@adv_ip}
s=-
c=IN IP[media_ip_type] [media_ip]
t=0 0
m=audio [media_port] RTP/AVP 0
a=rtpmap:0 PCMU/8000
      MSG
      start_media
      send msg, opts
    end
def send_answer(opts = {})
      opts[:retrans] ||= DEFAULT_RETRANS
      msg = <<-MSG

SIP/2.0 200 Ok
[last_Via:]
From: <sip:[$remote_addr]>;tag=[$remote_tag]
To: <sip:[$local_addr]>;tag=[call_number]
[last_Call-ID:]
[last_CSeq:]
Server: #{USER_AGENT}
Contact: <sip:[$local_addr];transport=[transport]>
Content-Type: application/sdp
[routes]
Content-Length: [len]

v=0
o=user1 53655765 2353687637 IN IP[local_ip_type] #{@adv_ip}
s=-
c=IN IP[media_ip_type] [media_ip]
t=0 0
m=audio [media_port] RTP/AVP 0
a=rtpmap:0 PCMU/8000
      MSG
      start_media
      send msg, opts
    end
Answer an incoming call

 @param [Hash] opts A set of options containing SIPp <send> element attributes