Connecting Remote Offices Using 3CX Bridges
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Connecting Remote Offices Using 3CX Bridges

Connecting 3CX Phone Systems (Bridges)

On this topic

Connecting 3CX Phone Systems (Bridges)

Introduction

Creating a Bridge

Step 1: Create a Bridge on the Master Phone System

Step 2: Create a Bridge on the Slave Phone System

See Also

Introduction

You can connect two separate 3CX Phone Systems together, allowing you to make calls between branch offices for free just by utilizing your existing internet connection.

A “Bridge” can be assigned a prefix, which you will dial to access the other 3CX Phone System. This prefix must be followed by the extension number you wish to reach on the other 3CX Phone System.

Alternatively, you can assign the extensions in one Office to start with one number (e.g. 100, 101, 102 where all extensions start with 1), and the extensions in the second Office to start with a different number (e.g. 200, 201, 202 where all extensions start with 2). This way, users from one office can directly dial the extension number without using a prefix making calling between offices or branches seamless. In this case, when the outbound rule is created, you must ensure that the prefix corresponds to the numbering plan selected and that no digits are stripped.

Creating a Bridge

A bridge can have 2 types: “Master” or “Slave”. When you create a bridge between 2 3CX Phone Systems, one end must be configured as a “Master” and the other end must be configured as a “Slave”.

When you create a bridge between two 3CX Phone Systems ensure that you first create the Master endpoint on one 3CX, and then create the Slave endpoint on the other 3CX. Follow this order when creating bridges to get the connection working quicker.

Step 1: Create a Bridge on the Master Phone System

  1. In the 3CX Management Console go to “Bridges” node and click "Add Bridge".
  2. Enter a name for the bridge and take note of the virtual extension number. (You will need this number when you create the “Slave” Bridge connection so ensure that the virtual extension number generated is not in use on the other 3CX Phone System which will host the “Slave” bridge endpoint).
  3. Type of 3CX Bridge - choose Master”.
  4. Specify a prefix to be used for this bridge. If you specify 6, then a you must dial 6100 to reach extension 100 on the other 3CX Phone System. You can also dial 600 to reach extension 600. This prefix is also used to redial missed calls between offices.
  5. Authentication Password – The password that will be used for authentication.

  1. The “Allow Tunneled Connection” option allows all SIP and RTP traffic to be sent via a single TCP port. The 3CX Tunnel vastly simplifies firewall configuration, reduces bandwidth and also secures your phone calls.
  • If “Allow tunneled connection” is enabled, enter the public IP address or FQDN of the “Slave” 3CX Phone System. In the example above “office2.3cx.com” is the FQDN of the office in New York.
  • Configure the 3CX Tunnel port of the New York 3CX Phone System. By default this is 5090. However in multiple instances installations or cloud installation this port will differ for each instance.

  1. Select if you want to publish and/or receive presence information to/from the New York 3CX Phone System.
  • Publish Information is available in Standard and Pro.
  • Receive information is available only with a  Pro Edition license.

  1. Configure the protocol (http or https) to be used to transfer presence data between 3CX Phone Systems and enter the FQDN of the remote 3CX. (If a tunneled connection is configured, this will be automatically populated). If the webserver of the New York 3CX Phone System is running on non default HTTP/HTTPS ports - example 5000 or 5001, then you need to specify the port after the FQDN example:
  • If the HTTP Port of the second pbx is 5000, specify: office2.3cx.com:5000
  • If the HTTPS Port of the second pbx is 5001, specify: office2.3cx.com:5001
  1. Select the users that are able to see this remote connection from within their 3CXPhone.
  2. Accept all other defaults and click “Next” to create the bridge.
  3. The “Outbound Rules” dialog will be presented. If a prefix was configured in the bridge Bridge type section, the same prefix will be automatically used for the outbound rule prefix and the bridge route will be set automatically. By default Strip Digits will be set to 1. You can change this setting and if you choose an extension numbering plan that does not require you to strip the prefix, set Strip Digits to 0.

Step 2: Create a Bridge on the Slave Phone System

  1. In the 3CX Management Console of the “Slave” 3CX Phone System, Select the “Bridges” node and click "Add Bridge".
  2. Enter a name for the bridge and assign the same virtual extension number as the one configured on the Master 3CX Phone System.
  3. Type of 3CX Bridge - choose “Slave.
  4. Specify a prefix to be used for this bridge. I.e. if you specify 7, then a you must dial 7100 to reach extension 100 on the other 3CX Phone System. It could also be that the extensions on the other pbx start with 7 example 706, 708 etc.
  5. Enter the Public IP or FQDN of the “Master” 3CX Phone System and the port.

  • If you selected “Use tunneled connection” in the port field you have to enter the Master’s Tunnel port e.g 5090.

  • If “Use tunneled connection” is not selected, then this slave connection is a direct bridge so in the port you have to enter the Master’s SIP port e.g 5060.
  1. Authentication Password – The password configured on the “Master” 3CX Phone System Bridge.
  2. Select if you want to publish and receive presence information from the other 3CX Phone System
  3. Configure the protocol, url and users for 3CX Presence.
  4. Accept all other defaults and click “Next” to create the bridge.
  5. If you have specified a prefix, the “Outbound Rules” window will open and automatically configure your chosen prefix as the outbound route for the new bridge.  By default Strip Digits will be set to 1. You can change this setting and if you choose an extension numbering plan that does not require you to strip the prefix, set Strip Digits to 0.

See Also

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