IESG Statement on Registration Requests for URIs Containing Telephone Numbers
Date: 3 Mar 2008
RFC4395: Guidelines and Registration Procedures for New URI Schemes
The IETF has found that there are many special cases when dealing with telephone numbers as identifiers or locators. Duplicating the special case logic in many different URIs is going to be error-prone as well as costly.
The IESG feels that since the Tel URI is quite extensible, extending it is the preferred approach over defining new URIs containing telephone numbers.