ring out
To make a phone call from an internal phone system to a general telephone network number.
ring out: call external from an internal phone system
Ring out is the act of placing a call from a private branch exchange (PBX) or internal phone system to a number on the public switched telephone network (PSTN). The caller dials from an internal extension and the system routes the call through a trunk line to the external network, charging the call to the company account or a specific cost center. This contrasts with ring in, where external calls come into the internal system.
In legacy systems, a user would dial a prefix (often 9) followed by the external number. The PBX would detect this prefix, seize an available trunk line, and pass the digits to the telephone company's switching equipment. Modern VoIP systems handle ring out similarly, using SIP trunks or other IP-based connections instead of physical analog or digital lines. The system tracks which extension originated the call for billing, security logging, and call accounting.
Common configurations and controls
Organizations typically restrict ring out rights by extension class or user role. A receptionist might have unlimited ring out permission, while a manufacturing floor extension might be blocked entirely or limited to toll-free numbers. Call accounting systems flag long-distance or international ring outs for cost management. Least-cost routing (LCR) logic can automatically choose the cheapest carrier for a ring out call, switching between traditional trunks, VoIP providers, or dedicated carriers depending on the destination and time of day.
Problems arise when trunk lines are exhausted during peak hours, forcing callers to hear a busy tone or fast busy signal. Security risks include unauthorized long-distance calls from poorly controlled extensions and toll fraud, where intruders exploit ring out to make expensive calls to premium numbers. Call detail records (CDRs) from the PBX provide the audit trail for both legitimate business analysis and fraud investigation.
The terminology reflects the physical motion of an older switchboard operator's actions: to ring out was to ring (call) someone out (external to the building). The term persists even though modern systems are purely electronic and the operator has been replaced by automated switching logic.