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firewall

Troubleshooting a Direct Remote Extension

February 10, 2012 - 8:03 pm | 7 Comments

This step by step guide will help you troubleshoot a direct remote extension setup at home or at a remote office. Direct remote extensions can work but correct functionality cannot be guaranteed as there are many factors at play (such as: Network Topology, Router configuration, Firewall settings, etc.) and you may not have control over all the devices involved to make the proper changes necessary for a direct remote extension

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What to look for when buying a router for use with 3CX Phone System

May 10, 2011 - 9:50 pm | 5 Comments

Purchasing a router may sound like a pretty simple task. This however can become somewhat challenging when VOIP comes into play. There a couple of core functions that your choice of router needs to perform so as to simplify your configuration for use with 3CX.

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Working Sonicwall Configuration for 3CX PhoneSystem

September 6, 2010 - 10:04 pm | 0 Comments

Many users are battling with Sonicwall devices, and even though 3CX cannot provide support for this, we have the following notes to hopefully help you with your configuration.

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Router Configuration for 3CX PhoneSystem

July 23, 2010 - 5:17 pm | 3 Comments

Correct Router Configuration is a key element in ensuring correct communications between 3CX PhoneSystem and external entities such as external extensions, VoIP Provider services, and other Bridged PBXs. NAT and/or PAT When a network host A sends a request to another network host B, it will be expecting a reply to the request. When both network hosts reside on a Public IP Address, the exchange is direct, and simple enough.

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Securing 3CX PhoneSystem – some hints!

June 14, 2010 - 11:09 pm | 5 Comments

If you have been asking yourself how to secure 3CX PhoneSystem, read on…

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Configuring a Draytek 2820 Router for 3CX with QoS configuration

May 24, 2010 - 11:47 am | 9 Comments

In this article we will describe the configuration of a hardware router with a very attractive quality-price ratio. The Draytek 2820 is a ADSL 2/2+ Router/Firewall with advanced features such as the capability to establish 32 VPN connections, a robust object-based firewall, QoS Management, Bandwidth Management, and Dual-WAN cabilities. We will look into NAT configuration for 3CX and QoS configuration to prioritize SIP and RTP traffic. The firmware version tested

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General Configuration Information when using VoIP Providers

May 3, 2010 - 2:20 pm | 3 Comments

This document will provide an overview of the more common concepts which need to be kept in mind when configuring 3CX PhoneSystem inside your network infrastructure, including the following topics: NAT Configuration STUN Resolution DNS Resolution in a VoIP environment Custom Configuration for particular network layouts Different types of VoIP Provider Accounts Custom Source Identification for VoIP Provider SIP message exchange

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Firewall Configuration Overview for 3CX PhoneSystem

March 29, 2010 - 2:57 pm | 0 Comments

In order for 3CX Phone System to communicate successfully with VoIP providers and Remote Extensions, your firewall/router device must be configured for SIP operation. To maximize your chances of success, make sure you choose a device that does not implement a SIP Helper or SIP ALG, or which can be configured to be disabled.

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Ports used by 3CX Phone System

November 3, 2009 - 7:29 pm | 0 Comments

The following is a complete list of ports that 3CX PhoneSystem uses in a default installation scenario:

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What is the firewall checker and why do I need it?

October 3, 2009 - 7:11 pm | 0 Comments

Introduction The 3CX Firewall Checker checks whether the ports needed to communicate with your VOIP provider are open and properly configured with STATIC Port mapping. If the firewall checker does not complete successfully, you will not be able to make or receive calls from a VoIP provider or external extension. Common symptoms that are linked to incorrect firewall configurations are: No registrations One-way audio Stun Problems, or incorrect resolution The

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Using the 3CX SIP Proxy Manager

September 3, 2009 - 7:21 pm | 0 Comments

Click to download the stand-alone SIP Proxy Manager What is the 3CX SIP Proxy manager The SIP Proxy Tunnel can combine all SIP (signaling) and RTP (media) VoIP Packets from one location (typically a remote office) and deliver them to and from another location (typically the PBX Server) using a custom TCP protocol. This simple concept allows us to exploit the SIP Proxy Tunnel to overcome difficult situations, or to

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External and Internal Devices: Network Topology

September 3, 2009 - 7:17 pm | 0 Comments

Introduction 3CX Phone System frequently communicates across LANs and establishes calls between devices (softphones, hardphones, gateways, VoIP providers, and PBX bridges) which are located on different networks. The PBX communicates both with devices that are inside the PBX’s LAN (internal devices), as well as with devices that are outside the PBX’s LAN (external devices). 3CX needs to adjust the SIP packets depending on whether a device is external or internal.

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Is Microsoft ISA server 2004 / 2006 supported as a firewall for VOIP?

August 3, 2009 - 7:00 pm | 0 Comments

The issues with Microsoft ISA server 2004 and 2006 Unlike most professional firewalls, Microsoft ISA server is not able to do static port mapping. Without static port mapping it is not possible to reliably connect to a VOIP provider or remote extensions. This is not a 3CX issue but an ISA server issue. The best solution is to buy a firewall such as from Linksys, Cisco, Netgear and others. Even

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How do I configure a CISCO router to allow connection to a VOIP provider?

June 3, 2009 - 6:46 pm | 0 Comments

If you are using a VOIP provider, then you will have to configure your firewall correctly in order to get reliable results. Your firewall must support STATIC PORT MAPPING. 3CX Phone System needs the following ports mapped on the router or firewall to operate properly: Port 5060 (TCP and UDP) – Used for SIP protocol transmission – must be a static mapping, no port translation Port 5090 (TCP) – Used

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DoS and Flood protection in Firewall Configuration

May 5, 2009 - 6:08 pm | 1 Comments

So you have installed 3CX PhoneSystem, your VoIP Provider account registers fine, a couple of test calls successfully prove that all is working. It’s now time to put things into production. And as soon as you have more than a couple of simultaneous calls, things stop working correctly!!! Calls do not come in, registrations fail, unexplained one-way-audio or no-audio behaviour – what gives?? Firewalls and NAT Devices today are always

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Why does 3CX require static port mappings (Full Cone NAT)?

May 3, 2009 - 6:53 pm | 0 Comments

If you are using a VOIP provider, you will need to have a firewall that supports and is configured to use static port mapping. Static port mapping is required for RTP, the protocol that carries audio, to be able to function correctly. RTP and Symmetric NAT VOIP applications use the RTP protocol to send and receive audio and video streams, tend to have problems behind a firewall or a router

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How do I configure my Linksys router for 3CX Phone System?

May 3, 2009 - 6:30 pm | 0 Comments

If you are using a VOIP provider, then you will have to configure your firewall correctly in order to get reliable results. Your firewall must support STATIC PORT MAPPING. 3CX Phone System needs the following ports mapped on the router or firewall to operate properly: Port 5060 (TCP and UDP) – Used for SIP protocol transmission – must be a static mapping, no port translation Port 5090 (TCP and UDP)

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What is QoS (Quality of Service)? A guide

April 3, 2009 - 6:25 pm | 0 Comments

In the VoIP / telecommunications  field, the term QoS (Quality of Service) refers to resource reservation control mechanisms. Quality of service is the ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow.  Quality of service guarantees are important for VoIP since VoIP is real time and requires fixed bit rate. QoS mechanisms are not required

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How and when can I switch off STUN Resolution?

March 1, 2009 - 3:48 pm | 0 Comments

How and when can I switch off STUN Resolution STUN resolution is necessary for the PBX to understand what it’s public IP Address is, and what port mappings are in effect for Media (to attempt NAT traversal when port forwarding is not implemented). STUN resolution may be disabled when: No External entities are in use (no bridges, voip providers, extensions) AND/OR Static Port Forwarding is in place for reliable media

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