Snom 370 SIP Phone Through NAT to 3CX matt April 13, 2009 Uncategorized 1 Comment My article relating to this was accepted and posted in the official 3CX blog. You can read it here. You Might Also Like Some cool natural parenting giveaways!! June 28, 2008 More Mead! February 8, 2009 Update November 18, 2009 This Post Has One Comment pcunite 28 Apr 2010 Reply For point number 4 reqarding the Keepalive Interval you write: —- 4. I set the STUN Interval to five minutes. I set the Keepalive Interval to 20 seconds. The Keepalive Interval needs to be shorter than the amount of time than your firewall keeps NAT translations around. You may need to play with this value. If it is too long you may not be able to receive incoming calls. —- It is more accurate to say that the Keepalive Interval keeps the UDP port from expiring and thus being closed by your router/firewall. Most routers will close an unused UDP port in 180 seconds. Leave a Reply Cancel reply Notify me of follow-up comments by email. Notify me of new posts by email. This site uses Akismet to reduce spam. Learn how your comment data is processed.