> Thank you for the suggestions. I am going to test the SIP trunking option
> since we have a PRI for backup purpose. This PRI uses only one DID. I have 19
> DID numbers left to play with. What I am thinking is getting either a Trixbox
> with an E1 card (I don't know if Mitel work with other cards) or just buy an
> e1 card and build the Asterisk server myself. I built one before just to make
> some test calls.

Excellent, you are going down a good path.

The one piece of advice I will give you regarding SIP trunking, since I went
through this before is:

Be thorough.  Really thorough.  Amazingly thorough.  And diligent too.  And
stubborn.  If the phone company tells you "That's normal" and you know it's
not normal, don't give in.  One of the phone companies I worked with told me
it was normal to drop small packets (such as ping) when the line was
overloaded.  They had a problem in their QoS, and unfortunately ... DNS is
made of small packets too.  So DNS was broken until I got them to fix it.

After it's supposedly all working, don't trust that they got it right.  Ask
them if QoS is finished now.  They'll say yes.

So place a call over that line, and another, and another.  Keep them all
open.  And run a continuous ping across the same line, and another and
another.  Now start FTP downloading something huge.  And another and
another.  

Do it all at the same time.  Monitor the line.  Measure your FTP throughput.
Listen for choppiness in the phone.  Look for packet drops in the pings.

Know the speed of your lines ... See if the performance of the line is
meeting expectations.

Now, dial into some automated service, such as 1-800-Dell or whatever.  Push
keys and be sure the other side receives the keypresses.  Now call some
other, and some other, and some other.  Test several different destinations.
They all use different handshaking techniques, and there's no guarantee that
the touch tones will be correctly handled, unless you specifically thought
about that and tested it.

I am telling you each of these things, because they are all problems I have
found before, when using SIP trunking.  It's far less mature than
traditional PRI or POTS.  Consequently, there are a lot of ways things can
go wrong, that the phone providers didn't think of, and haven't
proceduralized as well as they should.


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