How to block extensions being registered outside of the network (LAN)

Blocking 3CX extensions being registered outside of your network can be an important security step as users will not be able to make calls un unknown networks.

Step:

2. On 3CX Phone System Management Console. 

1. Click Extensions.

1. Select Extension. 
2. Click Edit. 

1. Click the Options tab.
2. Select Disallow use of extension outside the LAN. This will block extension in registering outside your network.
3. Click OK to apply changes.