[Asterisk-Users] VoIP dialtone?

[John Todd]

OK, this thread is getting really out of hand, so I'll condense my 
answers into one big stupid message:


1) 911 service.  Yes, that is one of three reasons to keep your PSTN 
line.  The other two reasons are:   Inbound calls from local callers 
still should work on a POTS line, for now.  You can't find VOIP 
providers in most area codes, so you'll most likely need to have a 
"local" number that finds it's way to you for "local" tasks. 
Secondly, the Internet is not as reliable as the phone system. 
Sorry, folks, it just works that way right now despite what your 
network engineer might tell you.  That's not to say it's unreliable, 
but those last two nines are very expensive... Besides, any good 
network engineer will tell you that you should have multiple paths 
for your IP connectivity.  With few exceptions, most homes do not 
have multipath connectivity.  (note: businesses may in fact have 
better uptime on their IP network than their phone network, if they 
have competent engineers and a reasonable budget.)

1.5) There are reasonable technical solutions to this problem, but 
for the life of me I can't figure out why the 911 centers haven't 
gotten their act together and solved this.  There are two halves to 
this problem: "What PSAP do I call? (and what phone number)"  and 
"How do I get my location data to the PSAP once I call them?" 
C'mon, this is not difficult.  The first question can be answered 
trivially: there _must_ be a database of address-to-PSAP mappings. 
Any PBX administrator (or SIP phone owner, for that matter) should be 
able to figure out their address.  Methods for associating the PSAP 
number with the phone are numerous, and trivially implemented - if 
people don't keep their address information updated, they're SOL 
(though you can remind them in an automated fashion to keep it 
updated - just forbid them from using the service unless they verify 
the address every month or so.)  The second question is more 
difficult, but certainly


2) Networks of Asterisk servers, offering dialtone to each other in 
different places.  YES, this is a good idea, but setting dialplans up 
for least-cost-routing via static routes is a pretty rotten task. 
See my conversations on why someone should implement TRIP in Asterisk 
(hey, I'm still looking for a programmer... anyone want some money?)
   http://lists.digium.com/pipermail/asterisk-dev/2003-July/001172.html

3) Well, I forget what 3 was.  Time to get some sleep.

JT