asterisk users - Jun 2010 - ISP down internal phones become unavailable

I saw the following lines in the log this morning. From my router logs
I see that the connection went down as my ISP was doing maintenance
for a few minutes last night. I can understand the external
registrations timing out, but why do the phones become unreachable.
They are on the internal lan within the same subnet as the Asterisk
server. Internal DHCP and DNS was functional. If I had a PRI card in
this system as well that would mean I couldn't make phone calls
because the Internet is down.

Ryan

[Jun 21 01:51:26] NOTICE[13657]: chan_sip.c:11569 sip_reg_timeout:
-- Registration for 'xxxxxxx at newyork.voip.ms' timed out, trying again
(Attempt #1)
[Jun 21 01:51:46] NOTICE[13657]: chan_sip.c:22943 sip_poke_noanswer:
Peer '1850' is now UNREACHABLE!  Last qualify: 15
[Jun 21 01:51:46] NOTICE[13657]: chan_sip.c:11569 sip_reg_timeout:
-- Registration for 'xxxxxxx at sip.flowroute.com' timed out, trying
again (Attempt #1)
[Jun 21 01:52:07] NOTICE[13657]: chan_sip.c:22943 sip_poke_noanswer:
Peer '1800' is now UNREACHABLE!  Last qualify: 7
[Jun 21 01:52:07] NOTICE[13657]: chan_sip.c:22943 sip_poke_noanswer:
Peer '1801' is now UNREACHABLE!  Last qualify: 11
[Jun 21 01:52:07] NOTICE[13657]: chan_sip.c:11569 sip_reg_timeout:
-- Registration for 'xxxxxxx at newyork.voip.ms' timed out, trying again
(Attempt #2)
  == Extension Changed 2028[ext-local] new state Unavailable for
Notify User 1850
[Jun 21 01:52:17] NOTICE[13657]: chan_sip.c:18314
handle_response_peerpoke: Peer '1800' is now Reachable. (10ms /
2000ms)
  == Extension Changed 2028[ext-local] new state Idle for Notify User 1850
[Jun 21 01:52:17] NOTICE[13657]: chan_sip.c:18314
handle_response_peerpoke: Peer '1801' is now Reachable. (14ms /
2000ms)
[Jun 21 01:52:22] NOTICE[13657]: chan_sip.c:18314
handle_response_peerpoke: Peer '1850' is now Reachable. (16ms /
2000ms)

On Mon, Jun 21, 2010 at 7:32 AM, Ryan Wagoner <rswagoner at gmail.com>
wrote:
> I saw the following lines in the log this morning. From my router logs
> I see that the connection went down as my ISP was doing maintenance
> for a few minutes last night. I can understand the external
> registrations timing out, but why do the phones become unreachable.
> They are on the internal lan within the same subnet as the Asterisk
> server. Internal DHCP and DNS was functional. If I had a PRI card in
> this system as well that would mean I couldn't make phone calls
> because the Internet is down.
>
I have a PRI, and when the Internet connection goes out so do my
phones.  I suspect it is some type of DNS issue.  I do have a SIP
trunk, and it appears that if I lose DNS to the SIP trunk, the entire
PBX is offline.  I have no actual proof of any of this, and have not
done any extensive testing to prove or disprove this.