PJSIP

PJSIP is the modern SIP channel driver in Asterisk, replacing the legacy chan_sip module. Built on the PJSIP library, it provides improved performance, better NAT traversal handling, multiple endpoint support per device, and is the recommended SIP stack for current VICIdial installations running Asterisk 16 or later.

How It Works in VICIdial

PJSIP configuration in VICIdial uses the pjsip.conf file (or the Asterisk realtime database) and is organized into distinct objects: endpoints, transports, authentication, AORs (Address of Records), and registrations. This modular approach provides more flexibility than the legacy chan_sip — for example, a single phone can register multiple endpoints, and transport settings (UDP, TCP, TLS, WebSocket for WebRTC) are managed independently.

When VICIdial 3.14+ is installed, PJSIP is typically the default channel driver. Carrier trunks are defined as PJSIP endpoints with associated authentication and registration objects. Agent phones connect as PJSIP endpoints as well, whether using hardware SIP phones, softphones, or WebRTC clients.

The PJSIP stack handles codec negotiation, DTMF mode configuration, and RTP media setup with improved reliability compared to chan_sip, particularly in NAT environments.

Why It Matters

PJSIP is the future of SIP in Asterisk and VICIdial. The legacy chan_sip module has been deprecated and will not receive new features. PJSIP offers better WebRTC support (critical for browser-based agent interfaces), improved TLS/SRTP security, and handles complex NAT scenarios more reliably.

For new VICIdial deployments, PJSIP should be the default choice. For existing installations still using chan_sip, migration to PJSIP is recommended when upgrading to Asterisk 18+. See the VICIdial setup guide for PJSIP configuration examples.