manufacturers providing different features in an effort to differentiate their products. Common capabilities include (manufacturers may have a different name for each capability): Auto attendant Auto dialing Automated directory services (where callers can be routed to a given employee by keying or speaking the letters of the employee's name) Automatic call distributor Automatic ring back Busy override Call blocking Call forwarding on busy or absence Call logging Call park Call pick-up Call transfer Call waiting Camp-on Conference call Custom greetings Customized abbreviated dialing (speed dialing) Direct inward dialing (DID) Direct inward system access (DISA) (the ability to access internal features from an outside telephone line) Do not disturb (DND) Follow-me, also known as find-me: Determines the routing of incoming calls. The exchange is configured with a list of numbers for a person. When a call is received for that person, the exchange routes it to each number on the list in turn until either the call is answered or the list is exhausted (at which point the call may be routed to a voice mail system). Interactive voice response Local connection: Another useful attribute of a hosted PBX is the ability to have a local number in cities in which you are not physically present. This service essentially lets you create a virtual office presence anywhere in the world. Music on hold Night service Public address voice paging Shared message boxes (where a department can have a shared voicemail box) Voice mail Voice message broadcasting Welcome message Interface standards Interfaces for connecting extensions to a PBX include: DECT – a standard for connecting cordless phones. Internet Protocol – For example, H.323 and SIP. POTS (plain old telephone service) – the common two-wire interface used in most homes. This is cheap and effective, and allows almost any standard phone to be used as an extension. proprietary – the manufacturer has defined a protocol. One can only connect the manufacturer's sets to their PBX, but the benefit is more visible information displayed and/or specific function buttons. Interfaces for connecting PBXs to each other include: DPNSS – for connecting PBXs to trunk lines. Standardized by British Telecom, this usually runs over E1 (E-carrier) physical circuits. Internet Protocol – H.323 and the Session Initiation Protocol (SIP) are IP-based solutions for multimedia sessions. Primary rate interface (ISDN) – Provided over T1 (23 bearer channels and 1 signaling channel) or E1 carriers. Proprietary protocols – if