ENUMPlus is an open source e164 service established May 01, 2008 by several members of the #pbxinaflash channel.
ENUMPlus simplifies ENUM configuration and supports any ENUM lookup source.
A FreePBX module has been developed and is currently in “testing” – the module allows easy modification of ENUM lookup sources and does not require an ENUMPlus account.
The service is quite similar to e164, however, registration permits immediate number verification as well as SIP URI validation. At this point, only SIP routing is permitted.
The userbase is tentatively limited to North America as the maintainers do not have a reliable (cheap) ITSP for terminating international calls for DID verification.
PBX in a Flash thread https://pbxinaflash.com/forum/showthread.php?p=26720#post26720