SIP (Session Initiation Protocol) trunks are connections over the Internet that carry voice or phone calls and connect with an ITSP (Internet Telephony Service Provider). The connections are easy from an Asterisk business phone system (or other IP based system) and can benefit the end user with much lower cost calls. There are several business VoIP companies that offer SIP trunk type of connections, some of which have slightly different offerings than others. Not all SIP trunks are identical, some offer unlimited calls at one monthly price, while others charge a metered fee based on the number of minutes. This may not be the only difference between offerings as we shall see. Below we explain some significant differences in types of SIP trunk connections.
Connecting your on-premise PBX to a SIP provider allows a total IP solution saving costs. Rather than connecting to a local phone service with traditional copper lines, using only SIPO offers tremendous advantages and cost savings.
SIP trunks can vary in the amount of "channels" or connections allowed. Some SIP providers only allow one connection per SIP account while others allow multiple connections with the same SIP account. The difference is substantial, in that a multiple SIP type of connection where several connections are allowed by the provider with one SIP account can be a big advantage for companies who need more inbound and outbound lines. The advantages of a multiple connection SIP trunk are: