Scope:This article outlines the reserved and permitted numbering schemes to use for extensions and features.Restricted Numbering0-99Reserved for internal use411Local Directory Assistance 611Customer Service811Call Before You Dig911Emergency933Emergency Testing988National Suicide Hotline600-699Reserved for 611 feature700-799Reserved for Call Parking Queues900-999Reserved for 911, 933, and 988 features5000Unregistered Login to Voicemail - Prompts for extension and password5001Registered Login to Voicemail - Prompts for password only9900Unregistered Login to Voicemail - Prompts for extension and password9901Registered Login to Voicemail - Prompts for password only9902Hot Desking Sign in7000-7999Reserved for 7+ext transfer to voicemail feature9900-9999Reserved for system featuresRecommended100-599User Extensions700-719Call Parks - No Ringback720-799Call Parks with Ringback800-899User Extensions1000-4999User Extensions5003-6999User Extensions8000-8999User Extensions9000-9099Auto Attendants9100-9199Call Queues (Excluding Call Parks)9200-9899Special Extensions (ie Forwarding Users, Call Routing Users, Analog/Paging Systems, Fax Users)