asterisk users - Feb 2007 - Problem on Asterisk to Register lines for out/in calls

Hi guys,

I have a customer with asterisk registering 100 lines from my Voip Provider.

In some times during a day we receive this messages:

[Feb 21 17:09:34] DEBUG[26223]: sched.c:204 sched_settime: Request to
schedule in the past?!?!
[Feb 21 17:09:34] DEBUG[26223]: sched.c:204 sched_settime: Request to
schedule in the past?!?!
[Feb 21 17:09:34] DEBUG[26223]: sched.c:204 sched_settime: Request to
schedule in the past?!?!
[Feb 21 17:09:34] NOTICE[26223]: chan_sip.c:7085 sip_reg_timeout: --
Registration for 'number1@sip.provider.com' timed out, trying again
(Attempt #3)
[Feb 21 17:09:34] NOTICE[26223]: chan_sip.c:7085 sip_reg_timeout: --
Registration for 'number2@sip.provider.com' timed out, trying again
(Attempt #3)

This message happen in all 100 lines.
After few minutes all lines can register in my softswitch.
This problem is not cyclical.

Sniffing the network, i saw that asterisk send a register message,
receive a 407 message and after instead send another register with
authentication header, send another register message without
authentication header.

In most part of the time this asterisk work fine, except for this
problems that happen 4 or 5 times per day.

What could be the cause of this problem ?

Thanks.

-- 
Frederico Madeira
fmadeira@gmail.com
www.madeira.eng.br