Q: Ekiga calls being interrupted in 20 seconds.
A: This is Ekiga specific issue which is not solved yet in official Ekiga release.
So for now possible solutions are:
Fixing DNS and making SRV records pass fine. If you are using router with DNS support please check its settings. If DNS server is beyond your control we suggest you change your DNS server to some public DNS server. Here is the list of public DNS servers.
New DNS should be specified in /etc/resolve.conf before currently used server.
Update Ekiga to development version
Here is a source of daily snapshots http://snapshots.seconix.com
For example for Ubuntu Gusty it can be done as explained in the wiki
1. Install pgp keys as explained in wiki 2. Register repository with: deb http://snapshots.ekiga.net/ubuntu/ gutsy main 3. Remove standard ekiga 4. Install the package ekiga-snapshot
After you've made these changes you can check how Ekiga works making a free test call to Echo test number as its explained at Ekiga page.