asterisk users - Nov 2006 - How to reduce latency and first real ring timing?

In this scenario, a person calls from his home over SIP to the Asterisk box,
which transcodes SIP to IAX and routes this call to a service provider over
IAX. Service provider forwards the call to PSTN and eventually the dialed
party gets the ring.

The caller hears ring going 6-7 times before the called party actually gets
the first ring. When he talks, there is a noticable latency in the
conversation. As for the first 6-7 rings, I am sure he is hearing fake
rings, sent by option 'r' in the dial command from the first Asterisk
box or
from the service provider's server. But why is there a noticable latency?

This Asterisk box is P-IV 1.8 GHz, 1.5 GB RAM, hosted and connected straight
to the fibre. There is no load on it and so processor is free for any kind
of processing.

In other scenario, everything works perfectly fine, which is my home,
connected to the same provider over IAX, home phones are on SIP, asterisk is
an old P-II in my basement connected to regular cable modem which we use for
the Internet.

Why the first user is having these problems and what can be done to avoid
it. Is his home Internet is not sending voice traffic fast enough to the
Asterisk box, or is it the transcoding, or is something wrong at the hosting
site which delays voice traffic to and from the service provider? How can I
figure this problem out?

-- 
Zeeshan A Zakaria
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