[asterisk-users] Strange problem

[Carlos Eduardo Langoni]

Hi folks!

I have an asterisk, version 1.4.22.2, with dahdi 2.1.0.4 and OpenR2 2.1.1.0.
Sometimes twice a day, sometimes after 3 days, all sip devices looses
registry, but asterisk doesn't show nothing strange, no error log, and
all calls in E1 trunk continue running, but sending to voicemail.

What could be this problem? What should I research do find a solution?

Thanks a lot!

Carlos