e164.org recently released our simple API for remote access to the ITSP registry. Details on the API interface are available from
http://www.e164.org/wiki/ProviderAPI
The API allows for automation to be built into ITSP systems so that updates to your own systems can in turn trigger updates to the e164.org system.
In conjunction with the API access, e164.org will be finalising its ITSP policy, the draft specifications are available from
http://www.e164.org/wiki/ITSPpolicy