Based on last months survey – ENUMPlus has been lacking some major documentation; thus we have released version 0.2.3 for immediate download.
We have also added some additional features such as lookup timeouts as well as the ability to disable the success message.
Download the latest release here while we add ISN lookups to our roster 
I was just wondering if it would be possible to use the Asterisk database to store a certain number of recent ENUM lookups (say the previous 500) and whenever someone calls a number, check the database for the routing first, and if it’s been previously looked up within a given timeframe, then use the previous result (either the SIP address, or the fact that the lookup failed) without doing another online lookup. The idea is to speed up call completion, so that if someone is calling a number repeatedly (because no one answers or it is busy) they don’t have to wait for the ENUM lookup every single time. I actually suspect that one reason ENUM lookups aren’t more widely used is due to the lookup delay, given that such a small percentage of lookups actually produce a usable result.
The implementation might be similar to the blacklist feature for incoming calls, where you check to see if the number is blacklisted before passing the call through. Here you’d need a couple pieces of additional data (besides the number being called), namely the previous disposition of the call and the system time since the previous lookup (if it’s too stale, you’d delete the previous result and do a new lookup).
You would need some way to go through the database and occasionally purge the stale listings (maybe once a day in the middle of the night), otherwise the database could grow to an unmanageable size.
Does anyone have any idea how big the e164 database is?
Currently :
e164.org Statistics
Allocations: 47,844,557
e164.org alone currently stands at 48,105,634 allocations. ENUMPlus queries 5 additional sources that do not release their allocation statistics.