scope:

The present document aims to lay out and organize the various available options for establishing ENUM or ENUM-like mechanisms for number portability, and to establish a correspondence between these available options and actual use cases that are currently under implementation or are expected to be so in the near future.

Also the present document introduces several use cases of current or proposed number portability solutions at this point toward all IP in 7 countries (Japan, US, Netherlands, Italy, Switzerland, Sweden, Finland) with the cooperation of experts from each country. They are newly described in Annex B in the revised version.