SIP Trunking
A VoIP technology that connects an on-premises phone system to the public telephone network over the internet.
SIP (Session Initiation Protocol) trunking is the method by which an existing on-premises PBX or IP-PBX connects to the public switched telephone network (PSTN) over the internet, replacing traditional ISDN or analog phone lines. A SIP trunk is essentially a virtual bundle of phone lines — each channel carries one simultaneous call, so a business buying 10 SIP channels can handle 10 concurrent calls.
SIP trunking is typically chosen by businesses that have already invested in on-premises PBX hardware (Asterisk, FreePBX, Cisco, Avaya) and want to modernize their PSTN connectivity without replacing the entire system. It significantly reduces per-minute calling costs compared to traditional carrier circuits and allows businesses to scale channels up or down on demand.
Zonitel provides SIP trunk services for businesses that need to connect an existing IP-PBX to our network. We support standard SIP configurations, provide dedicated SIP credentials per trunk, and offer redundant SIP proxy servers for failover. Businesses starting fresh may prefer Zonitel's fully hosted Cloud PBX, which eliminates the need for any local hardware.