There has been tremendous interest in the development of an Internet service which offers responses to queries about E.164 numbers. Examples of such queries are as follows: "Give the information needed (or the various possibilities)to communicate with the terminal whose E.164 number is xxxxxxx" "Give the information needed (or the various possibilities) to communicate with the subscriber who 'owns' the E.164 number xxxxxx" "Can a fax be sent to the E.164 number xxxxxxx?" "Which capabilities/services are supported by the terminal with E.164 number xxxxxxxx?" The goal of the BOF is to determine if an IETF working group should be chartered to do things such as: a) specify the architecture and protocols which clients use to query information about E.164 numbers. b) specify the architecture and protocols which servers use to aquire the information needed to respond to such queries. Examples of protocols and systems that have been proposed to solve these problems are: DNS, BCP, LDAP, WASL.... As these examples suggest, the problem is not yet precisely defined, and a part of the BOF is to be devoted to gaining rough consensus on the exact scope of the eventual WG. We shall have to decide if there are several different problems to be solved in several different ways, or a single problem to be solved in a single way, or indeed if the problem should not be solved by a new IETF working group. As a final open problem, it is not clear that the interest in this protocol is restricted to queries on E.164 numbers - some would like to extend the scope to deal with "queries about telephone numbers" more generally, which might include national, regional, and even private numbering plans as well as the International E.164 numbering plan. The BOF will have presentations and discussion on the following topics: a) Exactly which problem(s) should be within the scope of the new WG (if one is needed)? b) Proposals for Architectures and/or Protocols to solve the problem. By the end of the BOF the plan is have closure on at least the first of these topics.  There will be several presentations on concrete proposals as well.