[OpenSBC] OpenSBC ACK problem

[madar <lma...@mi...>]

Hi,

I'm using opensbc to connect our IMS and other SIP systems. Opensbc used in b2bua mode with rtp proxy.
Now every call goes through opensbc. It works fine, but I have a problem now.
When user1 calls user2 and the connection estabilished user1 sends an ACK message, but the sbc cannot forward it.

Here are the details:
USER1 -> OPENSBC SIP/SDP Request: INVITE sip:22...@mi...
OPENSBC -> USER1 SIP Status: 100 Trying
OPENSBC -> USER2-IMS-I-CSCF     SIP/SDP Request: INVITE sip:22...@mi...
USER2-IMS-I-CSCF -> OPENSBC SIP Status: 100 Trying
USER2-IMS-I-CSCF -> OPENSBC SIP Status: 180 Ringing
OPENSBC -> USER1 SIP Status: 180 Ringing
USER2-IMS-I-CSCF -> OPENSBC SIP/SDP Status: 200 OK
OPENSBC -> USER1 SIP/SDP Status: 200 OK
USER1 -> OPENSBC SIP Request: ACK sip:OPENSBC:5060
USER2-IMS-I-CSCF -> OPENSBC SIP/SDP Status: 200 OK
USER2-IMS-I-CSCF -> OPENSBC SIP/SDP Status: 200 OK
USER2-IMS-S-CSCF -> OPENSBC SIP Request: BYE sip:OPENSBC:5060
OPENSBC -> USER2-IMS-S-CSCF     SIP Status: 200 OK
OPENSBC -> USER1 SIP Request: BYE sip:user1@OPENSBC:43760
USER1 -> OPENSBC SIP Status: 200 OK

OpenSBC logs says the following:
DBG: [CID=0x0e62] RCV: enc=0 490 Bytes from RCVADDR: 80.98.72.216:RCVPORT: 57474:UDP (ACK sip:152.66.87.200:5060 SIP/2.0)
329591:19:39.482        DBG: [CID=0x0e62]
329591:19:39.482        DBG: [CID=0x0e62]       RECEIVE:  REQ: ACK (1)
329591:19:39.482        DBG: [CID=0x0e62]       FROM: sip:te...@va...
329591:19:39.482        DBG: [CID=0x0e62]       TO: sip:la...@mi...
329591:19:39.482        DBG: [CID=0x0e62]       XOR: FALSE
329591:19:39.482        DBG: [CID=0x0e62]       SRC: 80.98.72.216 PORT: 57474
329591:19:39.482        DBG: [CID=0x0e62]
329591:19:39.482        DBG: [CID=0x0e62] Unable to find ACK Transaction M2I2YzE0ZjlhYjJjNDVkYjVhN2JmODQ5NzY0NmMyMWI.86b1da53aa43dc118f9086ad22c1c4a5|z9hG4bK-
329591:19:39.482        DBG: [CID=0x0e62]
329591:19:39.482        DBG: [CID=0x0e62]       *** TRANSACTION DOES NOT EXIST ***
329591:19:39.482        DBG: [CID=0x0e62]       Message: ACK sip:152.66.87.200:5060 SIP/2.0
329591:19:39.482        DBG: [CID=0x0e62]       Call-Id: M2I2YzE0ZjlhYjJjNDVkYjVhN2JmODQ5NzY0NmMyMWI.
329591:19:39.482        DBG: [CID=0x0e62]
329591:19:39.482        INF: [CID=0x0e62] Event: Setting UA Core [Call] to handle event ACK
329591:19:39.482        DTL: [CID=0x0e62] Event: ---> UnknownTransaction - ACK

The IMS hungup the call after 30 sec, because it doeasn't get the ACK message.
Is it an opensbc bug or my configuration are wrong? I can provide more logs and traces if it's necessary.

Thanks
 madar @ Mobile Innovation Centre