ENUM allows you to register your conventional telephone number along with your VoIP number (also known as SIP URI) on free registrars such as e164.org. So when someone on Voxalot (or another service supporting ENUM) calls you on your normal number, Voxalot checks the ENUM database and if you have registered your number, Voxalot will route the call to the corresponding SIP URI, which will route the call for free. 

So, go ahead and register your telephone number and encourage your family and friends to register with e164.org, as more people register on ENUM, more calls will be routed for free.  Voxalot uses SIP Broker to perfrom ENUM lookups against the following roots:

e164.arpa

e164.org

e164.info

e164.televolution.net

enum.org