Howto:Overlap dialing in SIP
Overlapping INVITE Transactions
The INVITE transaction with incomplete destination number hangs out until replaced by a new INVITE transaction.
A new (replacing) INVITE transaction causes the existing one to be terminated with "484 Address Incomplete".
Conv.| Time | 172.16.16.109 | 172.16.16.180 | 172.16.16.107 | 0 |8,363 | INVITE SDP () | |SIP From: sip:IP230-1b-00-24@innovaphone.de To:sip:2@innovaphone.de | |(2060) ------------------> (5060) | | 0 |8,546 | 100 Trying| | |SIP Status | |(2060) <------------------ (5060) | | 0 |10,275 | INVITE SDP () | |SIP From: sip:IP230-1b-00-24@innovaphone.de To:sip:20@innovaphone.de | |(2060) ------------------> (5060) | | 0 |10,278 | 484 Address Incomplete | |SIP Status | |(2060) <------------------ (5060) | | 0 |10,282 | ACK | | |SIP Request | |(2060) ------------------> (5060) | | 0 |10,466 | 100 Trying| | |SIP Status | |(2060) <------------------ (5060) | | 0 |12,455 | INVITE SDP () | |SIP From: sip:IP230-1b-00-24@innovaphone.de To:sip:207@innovaphone.de | |(2060) ------------------> (5060) | | 0 |12,458 | 484 Address Incomplete | |SIP Status | |(2060) <------------------ (5060) | | 0 |12,462 | ACK | | |SIP Request | |(2060) ------------------> (5060) | | ----------------------------------------------------------------------------- 1 |12,469 | | INVITE SDP () |SIP From: sip:anonymous@172.16.16.180 To:sip:207@172.16.16.180 | | |(2059) ------------------> (2051) | ----------------------------------------------------------------------------- 0 |12,646 | 100 Trying| | |SIP Status | |(2060) <------------------ (5060) | | ----------------------------------------------------------------------------- 1 |13,504 | | 180 Ringing |SIP Status | | |(2059) <------------------ (2051) | ----------------------------------------------------------------------------- 0 |13,508 | 180 Ringing | |SIP Status | |(2060) <------------------ (5060) | | ----------------------------------------------------------------------------- 1 |15,690 | | 200 OK SDP () |SIP Status | | |(2059) <------------------ (2051) | 1 |15,695 | | ACK | |SIP Request | | |(2059) ------------------> (2051) | ----------------------------------------------------------------------------- 0 |15,699 | 200 OK SDP () | |SIP Status | |(2060) <------------------ (5060) | | 0 |15,718 | ACK | | |SIP Request | |(2060) ------------------> (5060) | | ----------------------------------------------------------------------------- 1 |16,598 | | BYE | |SIP Request | | |(5060) <------------------ (2155) | 1 |16,600 | | 200 OK | |SIP Status | | |(5060) ------------------> (2155) | ----------------------------------------------------------------------------- 0 |16,602 | BYE | | |SIP Request | |(2060) <------------------ (5060) | | 0 |16,607 | 200 OK | | |SIP Status | |(2060) ------------------> (5060) | |
No overlapping INVITE Transactions
The INVITE transaction with incomplete destination number is rejected immediately with "484 Address Incomplete".
The caller then invokes a new INVITE transaction with an extended destination number.
Conv.| Time | 172.16.16.109 | 172.16.16.180 | 172.16.16.107 | 0 |3,779 | INVITE SDP () | |SIP From: sip:IP230-1b-00-24@innovaphone.de To:sip:2@innovaphone.de | |(2060) ------------------> (5060) | | 0 |3,787 | 484 Address Incomplete | |SIP Status | |(2060) <------------------ (5060) | | 0 |3,796 | ACK | | |SIP Request | |(2060) ------------------> (5060) | | 0 |5,260 | INVITE SDP () | |SIP From: sip:IP230-1b-00-24@innovaphone.de To:sip:20@innovaphone.de | |(2060) ------------------> (5060) | | 0 |5,268 | 484 Address Incomplete | |SIP Status | |(2060) <------------------ (5060) | | 0 |5,272 | ACK | | |SIP Request | |(2060) ------------------> (5060) | | 0 |6,360 | INVITE SDP () | |SIP From: sip:IP230-1b-00-24@innovaphone.de To:sip:207@innovaphone.de | |(2060) ------------------> (5060) | | ----------------------------------------------------------------------------- 1 |6,370 | | INVITE SDP () |SIP From: sip:anonymous@172.16.16.180 To:sip:207@172.16.16.180 | | |(2051) ------------------> (2051) | ----------------------------------------------------------------------------- 0 |6,561 | 100 Trying| | |SIP Status | |(2060) <------------------ (5060) | | ----------------------------------------------------------------------------- 1 |7,511 | | 180 Ringing |SIP Status | | |(2051) <------------------ (2051) | ----------------------------------------------------------------------------- 0 |7,515 | 180 Ringing | |SIP Status | |(2060) <------------------ (5060) | | ----------------------------------------------------------------------------- 1 |8,497 | | 200 OK SDP () |SIP Status | | |(2051) <------------------ (2051) | 1 |8,502 | | ACK | |SIP Request | | |(2051) ------------------> (2051) | ----------------------------------------------------------------------------- 0 |8,507 | 200 OK SDP () | |SIP Status | |(2060) <------------------ (5060) | | 0 |8,518 | ACK | | |SIP Request | |(2060) ------------------> (5060) | | ----------------------------------------------------------------------------- 1 |10,435 | | BYE | |SIP Request | | |(5060) <------------------ (2172) | 1 |10,438 | | 200 OK | |SIP Status | | |(5060) ------------------> (2172) | ----------------------------------------------------------------------------- 0 |10,440 | BYE | | |SIP Request | |(2060) <------------------ (5060) | | 0 |10,445 | 200 OK | | |SIP Status | |(2060) ------------------> (5060) | |
Support
In version 6 innovaphone handled overlap dialing according to "Overlapping INVITE Transactions".
In version 7 innovaphone handles overlap dialing according to "No overlapping INVITE Transactions",
since most SIP clients get in trouble when a server waits for more dialing information without telling the client with "484 Address Incomplete".