This Recommendation defines the general principles and basic operational requirements of the voice-mail store‑and‑forward service provided by service providers using computer-controlled voice-mail systems and Voice-mail Store-and-Forward Units (Voice SFU). Although voice-mail system access will be, predominantly, from within the same country in which the Voice SFU is situated, this Recommendation sets out the minimum service requirements that should be fulfilled to allow international extension of the service. International extension of this service is achieved by the interconnection with one or more other Voice SFUs, across national boundaries using automated transit facilities for the purpose of transfer and delivery of voice-mail messages.