Summary:ASTERISK-10911: Resetting the SEQ number back to 0 without sending a new INVITE SSRC
Reporter:K Anderson (kanderson)Labels:
Date Opened:2007-11-28 11:33:08.000-0600Date Closed:2011-06-07 14:03:14
Status:Closed/CompleteComponents:. I did not set the category correctly.
Versions:Frequency of
Environment:Attachments:( 0) or03.dial.1196191137.snoop
Description:When a caller is placed on hold asterisk is resetting the SEQ number back to 0 without sending a new INVITE SSRC.  This is causing occasional one way audio with  my carrier and delays after retrieving callers from hold.  I have captures done on the PBX, my carrier (Bandwidth.com), and Level 3.  I am available for any additional information, patch tests, or special requests.  Thank you.
Comments:By: K Anderson (kanderson) 2007-11-28 11:35:26.000-0600


This is a capture from Level 3.  Look at packet 4865 from source IP, the SEQ number is 65535. The next packet from is packet 4867 the SEQ is set to 0.  They report that this would cause an audio issue on their equipment.

By: Joshua C. Colp (jcolp) 2007-11-28 12:40:47.000-0600

Does this only happen when hold is involved or otherwise as well?

By: K Anderson (kanderson) 2007-11-28 12:54:57.000-0600

File- This only when retrieving calls from hold.  

Just for the record my symptoms:
When calls are placed on hold and retrieved occasionally the PSTN side can not hear the IP or there is a 5 second delay.  Half of the time it is fine.

Bellow are the statements that we (Centrix, Bandwidth.com, and Level 3) have made.

1)  Audio packets are transmitted and received from Centrix equipment.
2) The issue can only be recreated if Bandwidth.com is utilized in the call path (ie. other carriers utilized by Centrix do not have the same issue).
3) The issue has effected all clients of Centrix, including those with no changes or interventions to their setup.
4) With or without the firewall active the problem still occurs.
5) The internal clock for the phone is within sync with the servers.
6) Disabling the network time protocol daemon (to eliminate any possible time shifts during a call) does not effect the issue.
7) A different pbx on a different subnet has the same issue.
8) A different phone on different Internet connection (ie DSL) has the same issue.
9) Limiting the codec to g711 or g729 has no effect.
10) The calling number or called number has no effect, issue occurs regardless.
11) Power cycling the phone or pbx has no effect.
12) There is no apparent break in the RTP stream.
13) Unassociated network traffic does not appear to be a factor.
14) There does not appear to be an correlation between CPU, memory,read/write cycles, or bandwidth utilization on the pbx.
15) Re-registration cycle during issue has no effect.
16) The no audio condition only occurs after a call is retrieved from hold.
17)  Some calls suffer from a five second delay which adheres to all the above findings (only with Bandwidth.com, occurs on different pbx or phone, number called/calling has no effect, ect).
18)  Assigning the phone a public IP thereby eliminating NAT does not correct the issue.
19) A phone on the same subnet as the pbx does not correct the issue.
20)  The issue appeared 'suddenly' after months of service with no correlations to changes made by Centrix Networks.
21)  The percentage of calls with issues fluctuates and has no known correlation to server functions or load.
22)  Replacing or resetting modem cards where they hand off to the SS7 network has no effect (level 3).

Thank you for your help

By: Joshua C. Colp (jcolp) 2007-11-28 12:57:32.000-0600

Well, the reason it goes to 0 is because the sequence number is represented as a 16-bit unsigned integer with a maximum value of 65535. Once it reaches that it wraps back around to 0.

By: K Anderson (kanderson) 2007-11-28 13:10:55.000-0600

That makes perfect sense.  Let me send your response to level 3 and as such it seems like it is there side after all.  If you would like I will add a note when I have a resolution.  I apologize for wasting your time, I am just so anxious to get this resolved I am responding to emails without thinking.  I need to slow down and put the pressure on Level 3.  Thank you.

By: Joshua C. Colp (jcolp) 2007-11-28 13:16:27.000-0600

Suspended since this is a provider issue. If you could keep me informed at jcolp@digium.com about how it goes with Level3. Peace.