Remote IP Phone Extensions (STUN)

Version 20160711
Remote IP Phone Extensions (STUN)
Goal of this Module
Correctly Implement IP Phones in remote Locations using STUN
Configuration of Remote Firewall
Provision a remote STUN extension
Usage of RPS
● Covered Module 1.3 Configure the Firewall (Server Side)
● A Supported IP Phone → IP Phone Running Minimum Firmware
● Functioning Mail Server (SMTP) → End User Needs to have
Welcome Email
● Access to Remote Firewall/Gateway
Supported STUN Phones
● Desktop IP Phones:
○ Fanvil
○ snom
○ Yealink
Benefits Using Teleworker (STUN)
Internal Call Capabilities to Remote Users
Dropship IP Phones
No Additional Hardware Required
Autodiscovery of your 3CX
Provisioning STUN Extensions - Admin
● Create/ Configure extension in 3CX
○ Make/Model
○ MAC Address
○ Remote Ports
● Increment SIP/RTP ports for each subsequent device
● Uncheck: Options → “Disallow use outside of LAN”
● Advice: Create NAT in remote Firewall → IP Phone
● Send Welcome Email
What is STUN?
● STUN (Session Traversal Utilities for NAT) is a Method to
○ Discover the Public IP Address (from a LAN)
○ Discover Firewall Port Mappings (from a LAN)
● STUN Server is your own PBX
Provisioning Remote Extensions - End User
● Reset Phone (if not a new device)
● Power Up Phone At Remote Location
● Phone Prompts for Login → From Welcome Email
○ Username: Extension Number
○ Password: Voicemail PIN
What is RPS?
● Automatically triggered when Provisioning Method is
● Binds MAC Addresses to (Provisioning)-URL
● Phone boots and retrieves URL
● After 2 Weeks MAC/URL is unlisted
● If STUN Extension shows the following symptoms:
○ No connection to server
○ Audio issues
○ Cannot Transfer or Hold or Resume Calls
● Check Remote Firewall for
○ SIP ALG → Disable it - Always
○ Check that NAT is Implemented
● More than One Stun Phone behind one router?
→ PBX Delivers Audio
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