[Asterisk-Users] Why is the internet connection important to LAN and PSTN calls?

[Brent Torrenga]

Out internet connection was out this morning. It seems that the SIP
extensions on our LAN were affected. Behavior like:

Call comes in over POTS to a TDM400P, there is a delay then before the Cisco
79[46]0's start to ring.
If we were lucky enough to get a call through, then we could not transfer
the call, or place the call on hold, or park the call.
Outbound calls seemed to have a delay between the time they were dialed at
the SIP phone and when they were connected.

I know this has been brought up before, in fact there is a bit of a
discussion going on now about DNS SRV (in sip.conf, set srvlookup=no, or put
all the phone ip's on /etc/hosts). But what is really causing the issue
here? Yes, it is DNS, or something related to DNS, but why does that have
anything to do with * trying to make a phone ring on the LAN?

I would think that by using qualify=yes for any outbound voip trunks we
avoid an issue of trying to call out is the net is down, but why are any
operations on the LAN affected?


Sincerely,

Brent A. Torrenga
brent.torrenga at torrenga.com

Torrenga Engineering, Inc.
907 Ridge Road
Munster, Indiana 46321-1771

+1 219 836 8918 x325 Voice
+1 219 836 1138 Facsimile
www.torrenga.com