This Recommendation sets out some preliminary guidelines for Administrations wishing to offer the optional reverse charging facility over international public data networks. It is recognized that this is a rapidly developing field at the present time and that the principle of offering such a facility should be pursued in the most flexible way possible in order to secure the interests of both users and Administrations. For this reason, this Recommendation outlines alternatives for accommodating reverse charging. The choice and application of a reverse charging facility is subject to bilateral agreement.