Caller ID Priority
This document serves as a technical reference for understanding SIP (Session Initiation Protocol) User Identification (UID) and Caller ID presentation within a telecommunications environment. It defines the hierarchical logic used when multiple Caller ID sources are available—such as from the trunk, outbound rules, or user extensions. By outlining the priority order and illustrating common call scenarios, this document ensures consistency, transparency, and accuracy in Caller ID presentation across all outbound communications.
The system decides which Caller ID to display based on the following order of priority:
Outbound Rule
Extension
Advanced SIP Settings
Scenario 1 Complete Override

Scenario 1 - Complete Override
Scenario 2 Extension Override

Scenario 2 - Extension Override
Scenario 3 Trunk Passthrough

Scenario 3 - Trunk Passthrough
Scenario 4 Outboard Rule Only

Scenario 4 - Outbound rule only
Scenario 5 Extension Only
Scenario 5 - extension only
Scenario 6 Mixed Configuration
Scenario 7 Outbound Rule with Extension

Scenario 7 - Outbound rule with extension
Scenario 8 No Caller ID Available

Scenario 8 - No caller ID available
Scenario | Caller on Trunk (Priority 1) | Caller ID on Outbound Rule (Priority 2) | Caller ID on Extension (Priority 3) | Final Caller ID Reflected | Logic Applied |
1. Complete Override1 | +18235550199 | +15460205678 | +15150101234 | +15460205678 | Outbound Rule overrides Trunk and Extension |
2. Extension Override | +1823555019 | (Empty) | +1515010123 | +1515010123 | Extension used when Outbound Rule empty |
3. Trunk Passthrough | +1823555019 | (Empty) | (Empty) | +1823555019 | Original Trunk Caller ID preserved |
4. Outbound Rule Only | (Empty) | +1546020567 | (Empty) | +1546020567 | Outbound Rule applied when Trunk empty |
5. Extension Only | (Empty) | (Empty) | +1515010123 | +1515010123 | Extension Caller ID used as fallback |
6. Mixed Configuration | +1823555019 | +1546020567 | (Empty) | +1546020567 | Outbound Rule overrides Trunk |
7. Outbound with Extension | (Empty) | +1546020567 | +1515010123 | +1546020567x` | Outbound Rule has higher priority than Extension |
8. No Caller ID Available | (Empty) | (Empty) | (Empty) | NO From USER | System default when no Caller ID configured |