PURPOSE AND SCOPE This document provides guidelines for the assignment of Vertical Service Codes (VSC) for which standardization or consistency is desired across all industry sectors in the Public Switched Telephone Network (PSTN). For the purposes of these guidelines@ VSCs are customer-dialed codes in the *XX or *2XX dialing format for touch tone and the 11XX or 112XX dialing format for rotary phones. They are used to provide customer access to features and services (e.g. call forwarding@ automatic callback@ etc.) provided by network service providers such as local exchange carriers@ interexchange carriers@ Commercial Mobile Radio Service (CMRS) etc. For example@ Call Forwarding is activated by dialing *72 or 1172. VSCs are assigned to features or services to enable consistent accessibility throughout the PSTN. The purpose of common/standard VSCs is to minimize customer confusion and provide a standard service access approach for features and services within multiple individual networks (multi-network applications). VSCs may be required and assigned for use across and/or among two or more networks on an internetwork basis (inter-network applications)@ where multiple networks must act upon a VSC in a consistent manner on a given call. Such assignments are to be made using the same VSC resource@ but will be identified separately from multi-network applications. It is not the intent of these Guidelines to allocate any specific range of VSCs for exclusive inter-network or multi-network use. These guidelines do not address VSCs used for single network applications (intra-network applications) within individual networks. Such proprietary usage is at the sole discretion and determination of the individual network.