Hi everybody,  I have a "one way audio" problem. My enviroment is:
 
xx.xx.63.75/27 = SER
xx.xx.63.68/27 = Natbox (linux iptables masquerade)
xx.xx.70.2/25 = STUN server
xx.xx.63.78/27 = PAP1 linksys AOR 2000
10.1.1.233/24 = PAP2 linksys AOR 2001 (behind NATbox with stun enable)
 
I have no audio from PAP1 to PAP2 when the call is made from PAP1 to PAP2, but when the call is made from PAP2 to PAP1 it works correctly.
 
I see on the natbox that the RTP packet is droped with unreachable cause (icmp messages).
 
This is the trace (ngrep) for the call from PAP1 to PAP2 on external interface of the natbox, where I can see STUN packets and the number udp port that the PAP willl be use (16444 to 16447).
The problem is natbox use other port (1173). I don't know if this problem is on natbox or stun server or PAP.
Can you helpme?
 
 
Thanks!!
 

U xx.xx.63.75:5060 -> xx.xx.63.68:5060
  INVITE sip:2001@xx.xx.63.68:5060 SIP/2.0..Record-Route: <sip:xx.xx.63.75;ftag=d1ccd3db9e31eb1fo0;lr=on>..Via: SIP/2.0/UDP
  xx.xx.63.75;branch=z9hG4bK52fb.41985863.0..Via: SIP/2.0/UDP xx.xx.63.78:5060;branch=z9hG4bK-57b1577f..From: 2000 <sip:5
  890000@xx.xx.63.75>;tag=d1ccd3db9e31eb1fo0..To: <sip:2001@xx.xx.63.75>..Call-ID: d6e2df8b-5193d32f@xx.xx.63.78..CSeq: 101
   INVITE..Max-Forwards: 16..Contact: 2000 <sip:2000@xx.xx.63.78:5060>..Expires: 240..User-Agent: Linksys/PAP2-2.0.10(L
  Sc)..Content-Length: 420..Allow: ACK, BYE, CANCEL, INFO, INVITE, NOTIFY, OPTIONS, REFER..Supported: x-sipura..Content-Type: app
  lication/sdp....v=0..o=- 29375 29375 IN IP4 xx.xx.63.78..s=-..c=IN IP4 xx.xx.63.78..t=0 0..m=audio 16472 RTP/AVP 18 0 2 4 8 9
  6 97 98 100 101..a=rtpmap:18 G729a/8000..a=rtpmap:0 PCMU/8000..a=rtpmap:2 G726-32/8000..a=rtpmap:4 G723/8000..a=rtpmap:8 PCMA/8
  000..a=rtpmap:96 G726-40/8000..a=rtpmap:97 G726-24/8000..a=rtpmap:98 G726-16/8000..a=rtpmap:100 NSE/8000..a=rtpmap:101 telephon
  e-event/8000..a=fmtp:101 0-15..a=ptime:30..a=sendrecv..                                                                       
#
U xx.xx.63.68:5060 -> xx.xx.63.75:5060
  SIP/2.0 100 Trying..To: <sip:2001@xx.xx.63.75>..From: 2000 <sip:2000@xx.xx.63.75>;tag=d1ccd3db9e31eb1fo0..Call-ID
  : d6e2df8b-5193d32f@xx.xx.63.78..CSeq: 101 INVITE..Via: SIP/2.0/UDP xx.xx.63.75;branch=z9hG4bK52fb.41985863.0..Via: SIP/2.0/U
  DP xx.xx.63.78:5060;branch=z9hG4bK-57b1577f..Record-Route: <sip:xx.xx.63.75;ftag=d1ccd3db9e31eb1fo0;lr=on>..Server: Linksys/P
  AP2-2.0.10(LSc)..Content-Length: 0....                                                                                        
#
U xx.xx.63.68:5060 -> xx.xx.70.2:3478
  .....*f..*f..*f..*f.                                                                                                          
#
U xx.xx.63.68:16444 -> xx.xx.70.2:3478
  .....OB..OB..OB..OB.                                                                                                          
#
U xx.xx.63.68:16445 -> xx.xx.70.2:3478
  ....................                                                                                                          
#
U xx.xx.63.68:16446 -> xx.xx.70.2:3478
  .......&...&...&...&                                                                                                          
#
U xx.xx.63.68:16447 -> xx.xx.70.2:3478
  ....#...#...#...#...                                                                                                          
#
U xx.xx.70.2:3478 -> xx.xx.63.68:16447
  ...$#...#...#...#.........@?.+?D.........+F..........+F.                                                                      
#
U xx.xx.63.68:5060 -> xx.xx.70.2:3478
  .....*f..*f..*f..*f.                                                                                                          
#
U xx.xx.63.68:16444 -> xx.xx.70.2:3478
  .....OB..OB..OB..OB.                                                                                                          
#
U xx.xx.70.2:3478 -> xx.xx.63.68:5060
  ...$.*f..*f..*f..*f..........+?D.........+F..........+F.                                                                      
#
U xx.xx.63.68:16445 -> xx.xx.70.2:3478
  ....................                                                                                                          
#
U xx.xx.63.68:16446 -> xx.xx.70.2:3478
  .......&...&...&...&                                                                                                          
#
U xx.xx.70.2:3478 -> xx.xx.63.68:16444
  ...$.OB..OB..OB..OB.......@<.+?D.........+F..........+F.                                                                      
#
U xx.xx.70.2:3478 -> xx.xx.63.68:16446
  ...$...&...&...&...&......@>.+?D.........+F..........+F.                                                                      
#
U xx.xx.63.68:5060 -> xx.xx.63.75:5060
  SIP/2.0 180 Ringing..To: <sip:2001@xx.xx.63.75>;tag=156298945b7d27i0..From: 2000 <sip:2000@xx.xx.63.75>;tag=d1ccd
  3db9e31eb1fo0..Call-ID: d6e2df8b-5193d32f@xx.xx.63.78..CSeq: 101 INVITE..Via: SIP/2.0/UDP xx.xx.63.75;branch=z9hG4bK52fb.4198
  5863.0..Via: SIP/2.0/UDP xx.xx.63.78:5060;branch=z9hG4bK-57b1577f..Record-Route: <sip:xx.xx.63.75;ftag=d1ccd3db9e31eb1fo0;lr=
  on>..Server: Linksys/PAP2-2.0.10(LSc)..Content-Length: 0....                                                                  
#
U xx.xx.70.2:3478 -> xx.xx.63.68:16444
  ...$.OB..OB..OB..OB.......@<.+?D.........+F..........+F.                                                                      
#
U xx.xx.63.68:5060 -> xx.xx.63.75:5060
  SIP/2.0 200 OK..To: <sip:2001@xx.xx.63.75>;tag=156298945b7d27i0..From: 2000 <sip:2000@xx.xx.63.75>;tag=d1ccd3db9e
  31eb1fo0..Call-ID: d6e2df8b-5193d32f@xx.xx.63.78..CSeq: 101 INVITE..Via: SIP/2.0/UDP xx.xx.63.75;branch=z9hG4bK52fb.41985863.
  0..Via: SIP/2.0/UDP xx.xx.63.78:5060;branch=z9hG4bK-57b1577f..Record-Route: <sip:xx.xx.63.75;ftag=d1ccd3db9e31eb1fo0;lr=on>..
  Contact: 2001 <sip:2001@xx.xx.63.68:5060>..Server: Linksys/PAP2-2.0.10(LSc)..Content-Length: 236..Allow: ACK, BYE, CANCE
  L, INFO, INVITE, NOTIFY, OPTIONS, REFER..Supported: x-sipura..Content-Type: application/sdp....v=0..o=- 659101 659101 IN IP4 20
  0.43.63.68..s=-..c=IN IP4 xx.xx.63.68..t=0 0..m=audio 16444 RTP/AVP 18 100 101..a=rtpmap:18 G729a/8000..a=rtpmap:100 NSE/8000.
  .a=rtpmap:101 telephone-event/8000..a=fmtp:101 0-15..a=ptime:30..a=sendrecv..                                                 
#
U xx.xx.63.75:5060 -> xx.xx.63.68:5060
  ACK sip:2001@xx.xx.63.68:5060 SIP/2.0..Record-Route: <sip:xx.xx.63.75;ftag=d1ccd3db9e31eb1fo0;lr=on>..Via: SIP/2.0/UDP 200
  .43.63.75;branch=0..Via: SIP/2.0/UDP xx.xx.63.78:5060;branch=z9hG4bK-5a4c9c84..From: 2000 <sip:2000@xx.xx.63.75>;tag
  =d1ccd3db9e31eb1fo0..To: <sip:2001@xx.xx.63.75>;tag=156298945b7d27i0..Call-ID: d6e2df8b-5193d32f@xx.xx.63.78..CSeq: 101 AC
  K..Max-Forwards: 16..Contact: 2000 <sip:2000@xx.xx.63.78:5060>..User-Agent: Linksys/PAP2-2.0.10(LSc)..Content-Length:
   0....                                                                                                                        
#
U xx.xx.63.78:16472 -> xx.xx.63.68:16444
  ..8...-..L....@.....tF.34..V.|B..n..a.k(.R                                                                                    
#
I xx.xx.63.68 -> xx.xx.63.78 3:3
  ....E..F.........+?N.+?D@X@<.2....8...-..L....@.....tF.34..V.|B..n..a.k(.R                                                    
#
U xx.xx.63.68:1173 -> xx.xx.63.78:16472
  ..!o..vy.F.!...|...&.T.BP..Z..n...:.3..d..                                                                                    
#
U xx.xx.63.78:16472 -> xx.xx.63.68:16444
  ..8......L... .s..._exR..Kc.....+.O<.RZ.O{                                                                                    
#
I xx.xx.63.68 -> xx.xx.63.78 3:3
  ....E..F.........+?N.+?D@X@<.2....8......L... .s..._exR..Kc.....+.O<.RZ.O{                                                    
#
U xx.xx.63.68:1173 -> xx.xx.63.78:16472
  ..!p..wi.F.!.'D.F...K....@C..e.Z.[~P...Et,                                                                                    
#
U xx.xx.63.78:16472 -> xx.xx.63.68:16444
  ..8.../..L......@H..._...,[.P...rU.A..P...                                                                                    
#
I xx.xx.63.68 -> xx.xx.63.78 3:3
  ....E..F.........+?N.+?D@X@<.2....8.../..L......@H..._...,[.P...rU.A..P...                                                    
#
U xx.xx.63.68:1173 -> xx.xx.63.78:16472
  ..!q..xY.F.!....Mf.....Fu.Q.....~.}....v..                                                                                    
#
U xx.xx.63.78:16472 -> xx.xx.63.68:16444
  ..8...0..L..\.~..h..+..|S.C.M..~6W}....6sR                                                                                    
#
I xx.xx.63.68 -> xx.xx.63.78 3:3
  ....E..F.........+?N.+?D@X@<.2....8...0..L..\.~..h..+..|S.C.M..~6W}....6sR                                                    
#
U xx.xx.63.68:1173 -> xx.xx.63.78:16472
  ..!r..yI.F.!x|..Eo..._.1...;..GRz....*.x.Z                                                                                    
#
U xx.xx.63.78:16472 -> xx.xx.63.68:16444
  ..8...1..L..x.....n."..6.v....S.D.......S.                                                                                    
#
I xx.xx.63.68 -> xx.xx.63.78 3:3
  ....E..F.........+?N.+?D@X@<.2.!..8...1..L..x.....n."..6.v....S.D.......S.                                                    
#
U xx.xx.63.68:1173 -> xx.xx.63.78:16472
  ..!s..z9.F.!0...ooPE..F. .5...E....v......                                                                                    
#
U xx.xx.63.78:16472 -> xx.xx.63.68:16444
  ..8...2..L..z....+.b..r?...r....|..$.x...^                                                                                    
#
I xx.xx.63.68 -> xx.xx.63.78 3:3
  ....E..F.........+?N.+?D@X@<.2....8...2..L..z....+.b..r?...r....|..$.x...^                                                    
#
U xx.xx.63.68:1173 -> xx.xx.63.78:16472
  ..!t..{).F.!.o...{..r..3....F.$.r.. V..by.                                                                                    
#