Unstable USA toll free call routing
 

On the Smart Call List (Dial Plans) page there is a 'Dial Plan Test' function. I have been testing it with a US toll free number and am getting three different results which I have pasted below. The 3 differnet results seem to come up at random and without any changes to the dial plan between trials. The only match in my dial plan is _1NxxNxxxxxx and that is for webcalldirect, however I would prefer that US toll free numbers always route to a free service. Why is this routing unstable? How can I make sure that toll free numbers are intercepted by Voxalot and sent to one their free call termination services?
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A call to:18665734678 will get forwarded to sip:16416418665734678@sip.tollfreegateway.com

A call to:18665734678 will get forwarded to sip:18665734678@tf.voipmich.com

A call to:18665734678 will get forwarded to sip:0018665734678@sip.webcalldirect.com
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The variations are due to ENUM lookups. If you dont want ENUM then go into the dial plan entry and turn it off.
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I recognize the first two as an ENUM lookup. I would guess the third trial call failed the ENUM lookup for some reason. To always route toll free calls here is what I put in my Smart Calls plan:
The priority for these must be placed before your _1NxxNxxxxxx dial plan.

So this number (18665734678) has an ENUM match? Does that mean they have a SIP phone of some kind and a call to that number could be VoIP end to end without touching the POTS phone system?

I have now created dial plans to match toll free numbers. Is it a good idea to enable ENUM on these toll free number dial plans? I would think so, if the path can be VoIP end to end then the call quality should be better.

Is there a web site where I can enter a number to check if it is ENUM listed and find it's SIP address?

You can use ours SIPBroker - ENUM Lookup
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Looks like one can do an ENUM lookup with dig:
[boatman@localhost ~]$ dig +short 9.8.0.5.7.8.6.6.1.5.1.e164.org any
100 10 "u" "E2U+SIP" "!^\\+15166875089$!sip:15166875089@tx2.supernettel .com!" .
[boatman@localhost ~]$

This is interesting, I got two matches on 18665734678. I wonder if they are real SIP addresses or if this is just a way of routing toll free numbers?
[boatman@localhost ~]$ dig +short 8.7.6.4.3.7.5.6.6.8.1.e164.org any
200 10 "u" "E2U+SIP" "!^\\+1866(.*)$!sip:1866\\1@tf.voipmich.com!" .
200 10 "u" "E2U+SIP" "!^\\+1866(.*)$!sip:1641641866\\1@sip.tollfreegate way.com!" .
[boatman@localhost ~]

nslookup works too:
nslookup -sil -type=naptr 8.7.6.4.3.7.5.6.6.8.1.e164.org
Non-authoritative answer:
8.7.6.4.3.7.5.6.6.8.1.e164.org naptr = 200 10 "u" "E2U+SIP" "!^\\+1866(.*)$!sip:1866\\1@tf.voipmich.com!" .
8.7.6.4.3.7.5.6.6.8.1.e164.org naptr = 200 10 "u" "E2U+SIP" "!^\\+1866(.*)$!sip:1641641866\\1@sip.tollfreegate way.com!" .

I am surprised there doesn't seem to be an ENUM match for 61282062533, the Voxalot phone number!

It appears at least one of these providers has severe audio issues (it sounds like Darth Vader from Star Wars). I frequently have to dial a toll-free number several times to avoid it.