What is a SIP trunk?
A SIP trunk is a virtual connection that links a business phone system to the public telephone network over the internet using the SIP protocol.
Why it matters for sales teams
SIP trunks replace physical phone lines. Instead of renting a fixed number of circuits, a business buys capacity in channels, where each channel carries one call at a time. Adding capacity is a configuration change, not an installation.
For a sales team, a SIP trunk matters when the company runs its own PBX, or when IT asks how a dialer connects to the phone network. For teams using a hosted sales dialer or cloud phone system, the provider handles it.
Example
A company has an on-premises PBX with 40 extensions. Rather than renewing its old phone lines, it connects the PBX to a SIP trunk provider over the internet. The company's phone numbers move to the trunk, and outside calls now travel as VoIP until they reach the public network.
SIP trunk vs VoIP
VoIP is the broad technology of sending voice over IP networks. SIP (Session Initiation Protocol) is a signaling protocol that VoIP systems use to set up, manage and end calls. A SIP trunk is one specific use of it: the connection between a phone system and a carrier.