What Is a PRI Line?
A Primary Rate Interface (PRI) is a physical ISDN circuit that delivers 23 voice channels over a single T1 line. It requires on-site hardware, a 12–24 month contract, and a telecom technician to provision changes.
What Is SIP Trunking?
Session Initiation Protocol (SIP) trunking delivers voice calls over your existing internet connection. Channels are virtual, provisioned in minutes, and you only pay for what you use.
Side-by-Side Comparison
- Cost: PRI ~$800/mo fixed vs SIP pay-per-channel
- Scalability: PRI requires new hardware vs SIP scales in seconds
- Disaster recovery: PRI fails if the physical line fails vs SIP failover to any location
- International: PRI is domestic-only vs SIP supports global DIDs
The Verdict
For modern outbound call centers, SIP trunking wins on every metric. FlareDial's SIP trunks include number porting, geographic DIDs, and built-in failover.