This blog post will explain what direct inward dialing is. It is a service offered by an internet telephony service provider that provides direct dial phone numbers for usage with a PBX. PBX stands for private branch exchange. SIP trunking enables direct inward dialing service. The SIP protocol takes care of phone calls via the Internet by starting, managing, and ending them. Direct inward dialing is a service that allows external callers to make a direct call to an extension on a PBX. The need for a receptionist or a switchboard is not needed because calls to direct dial numbers will ring directly to an extension or ring group. Direct dial numbers are different from internal extensions because those only enable internal calls within the PBX. Depending on what type of PBX is used, a direct dial number can be linked to other services with an inbound route. Services include ring groups, text to speech announcements, and interactive voice response systems. PBXs can be hardware or software. Direct dial numbers have to be purchased with a set amount of channels. They can be a local, international, or toll free number. Direct dial numbers look just like regular phone numbers. Direct inward dialing enabled by SIP trunking enables a person to use their direct dial number on any SIP enabled softphone or hardware phone they are allowed to. There are many advantages to using direct inward dialing service. A better experience can be provided to callers due to being able to ring an extension or ring group directly without going through an auto attendant. Businesses that operate in different areas can setup local phone numbers for customers to reach them in their area. Calls can be routed by an internet telephony service provider via SIP trunking. Calls to direct dial numbers can be tracked for marketing purposes. Suppose a business operates a hotline for marketing campaigns, calls to those numbers can be looked at. That would enable a business to connect a caller to the right person or department. Most PBXs have analytics capabilities that can go through call reports to check the duration of each call or if the caller hangs up the phone. Adding and removing direct dial numbers to and from a PBX is easy. Internet telephony service providers allow their customers to add and remove direct dial numbers from their account.