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Extensions Management Overview

Extensions are the foundation of your OPBX phone system. This document explains what extensions are, the different types available, and how they work within your organization.

What Are Extensions?​

In OPBX, an extension is a phone endpoint that can receive calls. Extensions can represent:

  • User phones - Individual employee extensions
  • Conference rooms - Multi-party conference bridges
  • Ring groups - Groups of extensions that ring together
  • IVR menus - Automated call routing systems
  • AI assistants - Virtual assistants that handle calls
  • External forwards - Forwarding to outside numbers

Each extension has a unique extension number (e.g., 101, 102, 200) that callers can dial to reach it.

Extension Numbering​

Number Format​

Extension numbers in OPBX:

  • Are typically 3-4 digits long
  • Must be unique within your organization
  • Can start with any digit (though 0 is often reserved for operators)

Numbering Best Practices​

Consider organizing extensions by department:

RangeDepartmentExamples
100-199Management101 (CEO), 102 (CTO)
200-299Sales201 (Sales Manager), 210-220 (Sales Team)
300-399Support301 (Support Manager), 310-330 (Support Agents)
400-499Conference Rooms400 (Main Conference), 401 (Meeting Room A)
500-599Ring Groups500 (Sales Ring Group), 501 (Support Ring Group)
600-699IVR/AI600 (Main IVR), 601 (AI Assistant)
tip

Choose a numbering scheme that works for your organization and document it for future reference.

Extension Types​

OPBX supports multiple extension types, each designed for different use cases:

User Extension​

Direct extension assigned to a specific user for making and receiving calls.

Features:

  • SIP credentials for phone registration
  • Voicemail support
  • Outbound calling capability
  • Requires user assignment

Conference Room​

Multi-party conference bridge allowing multiple callers to join a single call.

Features:

  • PIN protection (optional)
  • Multiple participants
  • No user assignment required

Ring Group​

Routes incoming calls to multiple extensions simultaneously or sequentially.

Features:

  • Multiple members
  • Ring strategies (simultaneous, round-robin)
  • Fallback destination
  • No user assignment required

IVR Menu​

Interactive Voice Response system that routes calls based on caller input.

Features:

  • Key press routing ("Press 1 for Sales")
  • Multi-level menus
  • Custom greetings
  • No user assignment required

AI Assistant​

AI-powered virtual assistant that can answer and handle calls.

Features:

  • Natural language processing
  • Call handling automation
  • Integration with AI providers
  • No user assignment required

Call Forwarding​

Forwards incoming calls to an external phone number.

Features:

  • External number forwarding
  • No user assignment required
  • Simple configuration

AI Load Balancer​

Routes calls to AI Assistant Load Balancers with distribution algorithms.

Features:

  • Distributes calls across AI assistants
  • Load balancing algorithms
  • No user assignment required

Extension Status​

Extensions have a status that controls their availability:

Active​

  • Extension can receive calls
  • Shows as available in the system
  • Counts toward license usage

Inactive​

  • Extension cannot receive calls
  • Preserved for future use
  • Does not count toward license usage
  • Configuration is retained

Extensions and Users​

The relationship between extensions and users varies by extension type:

User Extensions (One-to-One)​

User extensions are special because they:

  • Require a user assignment
  • Can make outbound calls
  • Have voicemail boxes
  • Have SIP credentials for phone registration
User (John Smith) ←→ Extension 101 (Assigned)

Other Extension Types (Standalone)​

All other extension types:

  • Do not require user assignment
  • Cannot make outbound calls
  • Are configured independently
Extension 500 (Ring Group) → Routes to multiple users
Extension 400 (Conference) → Anyone can join
Extension 600 (IVR) → Routes based on caller input

Extension Features​

Voicemail​

Available for User Extensions only. Voicemail allows callers to leave messages when the user is unavailable.

SIP Credentials​

Available for User Extensions only. SIP credentials enable phones to register and make/receive calls.

Call Forwarding​

Available for User Extensions only. Forward calls to another number when the user is unavailable.

Caller ID​

All extensions can have a caller ID name associated with them.

Extension Management​

Creating Extensions​

Extensions can be created through the OPBX web interface or API. When creating an extension, you specify:

  • Extension number
  • Extension type
  • Configuration (type-specific)
  • Status (active/inactive)

Editing Extensions​

Extension settings can be modified after creation:

  • Extension number (with restrictions)
  • Type (some conversions allowed)
  • Configuration
  • Status

Deleting Extensions​

Extensions can be permanently deleted when no longer needed. Note:

  • User extensions should be unassigned from users first
  • Check routing rules before deleting
  • Historical call data is preserved

Extension Limits​

Extension limits depend on your OPBX plan:

PlanExtension LimitNotes
StarterUp to 10Good for small teams
BusinessUp to 50Suitable for growing businesses
EnterpriseUnlimitedFor large organizations

Contact your administrator or check your subscription details to see your current limit.

Next Steps​

Learn more about working with extensions:

Related Documentation: