ситуяция такова:
звонок с ОХЕ по IP идет нормально, проблема возникает при входящем звонке по IP т.е. стабильно обрыв соединения через 20 сек.

трасса входящего звонка

______________________________________________________________________________
| (599798:001438) Physical-Event :
| long: 79 desti: 0 source: 0 cryst: 0 cpl: 2 us: 0 term: 0 type a5
| tei: 0 >>>> message received : SETUP [05] Call ref : 00 0a
| SENDING COMPLETE
|______________________________________________________________________________
|
| IE:[04] BEARER_CAPABILITY (l=3) 80 90 a3
| IE:[18] CHANNEL (l=1) a3 -> T2 : Any B channel
| IE:[6c] CALLING_NUMBER (l=5) -> 01 80 Num : 199
| IE:[70] CALLED_NUMBER (l=4) -> 80 Num : 406
| [97] Locking shift. codeset : 7
| IE:[06] EI_IP_PAYLOADS (l=4) : (COMP/ECE/VAD)
| -> G711a/0/0 G723/0/0 G729/0/0 G711u/0/0
|
| IE:[0a] EI_RTP_INFO (l=30)
| -> stop_packet=0 stop_rtp=0 h323=1 wc=0 rf=0 udp=0 rqm=0
| -> Transm_Bande=0 detection_Q23=1
| -> Port RTP = 2158, IPv4 : 192. 168. 254. 2.
| -> Port RTCP SR = 2159, IPv4 : 192. 168. 254. 2.
| -> Port RTCP RR = 2157, IPv4 : 192. 168. 254. 2.
| -> Port Fax = 0, IPv4 : 0. 0. 0. 0.
|______________________________________________________________________________

______________________________________________________________________________
| (599798:001440) 1442: Send_IO1 (link-nbr=2, sapi=0, tei=0) :
| long: 29 desti: 0 source: 15 cryst: 0 cpl: 2 us: 8 term: 0 type a5
| tei: 0 <<<< message sent : CALL PROC (02) Call ref : 80 0a
|______________________________________________________________________________
|
| [9f] Non-locking shift. codeset : 7
| IE:[07] EI_IP_QOS (l=3) b8 a0 00
| IE:[18] CHANNEL (l=3) a8 83 81 -> T2 : No B channel
|______________________________________________________________________________

______________________________________________________________________________
| (599798:001441) 1442: Send_IO1 (link-nbr=2, sapi=0, tei=0) :
| long: 59 desti: 0 source: 15 cryst: 0 cpl: 2 us: 8 term: 0 type a5
| tei: 0 <<<< message sent : ALERT (01) Call ref : 80 0a
|______________________________________________________________________________
|
| [9f] Non-locking shift. codeset : 7
| IE:[06] EI_IP_PAYLOADS (l=1) -> G711a Ece 1 Vad 0
| [9f] Non-locking shift. codeset : 7
| IE:[0a] EI_RTP_INFO (l=30)
| -> stop_packet=0 stop_rtp=0 h323=0 wc=0 rf=0 udp=0 rqm=0
| -> Transm_Bande=1 detection_Q23=1 dtmf_payload=96
| -> Port RTP = 32760, IPv4 : 192. 168. 254. 15.
| -> Port RTCP SR = 32761, IPv4 : 192. 168. 254. 15.
| -> Port RTCP RR = 32761, IPv4 : 192. 168. 254. 15.
| -> Port Fax = 32763, IPv4 : 192. 168. 254. 15.
| IE:[1e] PROGRESS_ID (l=2) 81 88
|______________________________________________________________________________

______________________________________________________________________________
| (599798:001443) 1442: Send_IO1 (link-nbr=2, sapi=0, tei=0) :
| long: 55 desti: 0 source: 15 cryst: 0 cpl: 2 us: 8 term: 0 type a5
| tei: 0 <<<< message sent : FACILITY [62] Call ref : 80 0a
|______________________________________________________________________________
|
| [9f] Non-locking shift. codeset : 7
| IE:[06] EI_IP_PAYLOADS (l=1) -> G711a Ece 1 Vad 0
| [9f] Non-locking shift. codeset : 7
| IE:[0a] EI_RTP_INFO (l=30)
| -> stop_packet=0 stop_rtp=0 h323=0 wc=0 rf=0 udp=0 rqm=0
| -> Transm_Bande=1 detection_Q23=1 dtmf_payload=96
| -> Port RTP = 32760, IPv4 : 192. 168. 254. 15.
| -> Port RTCP SR = 32761, IPv4 : 192. 168. 254. 15.
| -> Port RTCP RR = 32761, IPv4 : 192. 168. 254. 15.
| -> Port Fax = 32763, IPv4 : 192. 168. 254. 15.
|______________________________________________________________________________

______________________________________________________________________________
| (599810:001445) 1442: Send_IO1 (link-nbr=2, sapi=0, tei=0) :
| long: 55 desti: 0 source: 15 cryst: 0 cpl: 2 us: 8 term: 0 type a5
| tei: 0 <<<< message sent : CONNECT (07) Call ref : 80 0a
|______________________________________________________________________________
|
| [9f] Non-locking shift. codeset : 7
| IE:[06] EI_IP_PAYLOADS (l=1) -> G711a Ece 1 Vad 0
| [9f] Non-locking shift. codeset : 7
| IE:[0a] EI_RTP_INFO (l=30)
| -> stop_packet=0 stop_rtp=0 h323=0 wc=0 rf=0 udp=0 rqm=0
| -> Transm_Bande=1 detection_Q23=1 dtmf_payload=96
| -> Port RTP = 32760, IPv4 : 192. 168. 254. 15.
| -> Port RTCP SR = 32761, IPv4 : 192. 168. 254. 15.
| -> Port RTCP RR = 32761, IPv4 : 192. 168. 254. 15.
| -> Port Fax = 32763, IPv4 : 192. 168. 254. 15.
|______________________________________________________________________________

______________________________________________________________________________
| (599811:001447) Physical-Event :
| long: 18 desti: 0 source: 0 cryst: 0 cpl: 2 us: 0 term: 0 type a5
| tei: 0 >>>> message received : CONNECT ACK (0f) Call ref : 00 0a
|______________________________________________________________________________

______________________________________________________________________________
| (600191:001448) Physical-Event :
| long: 22 desti: 0 source: 0 cryst: 0 cpl: 2 us: 0 term: 0 type a5
| tei: 0 >>>> message received : RELEASE [4d] Call ref : 00 0a
|______________________________________________________________________________
|
| IE:[08] CAUSE (l=2) 81 a9 -> [a9] TEMPORARY FAILURE
|______________________________________________________________________________

______________________________________________________________________________
| (600191:001449) 1442: Send_IO1 (link-nbr=2, sapi=0, tei=0) :
| long: 22 desti: 0 source: 15 cryst: 0 cpl: 2 us: 8 term: 0 type a5
| tei: 0 <<<< message sent : REL COMP [5a] Call ref : 80 0a
|______________________________________________________________________________
|
| IE:[08] CAUSE (l=2) 81 90 -> [90] NORMAL CALL CLEARING
|______________________________________________________________________________

Попробуйте в IP параметрах убрать Round Trip Delay request