PBX>Extensions>Extensions steps are followed.
We can start adding internals on the page that opens. 
ADD : Used to add internals one by one.
BULK ADD : Used to add more than one internal at the same time.
BULK EDIT : It is used to perform an operation in bulk by selecting more than one extension.
Internal Settings
Extension : The internal number is given in this section.
Max Registrations : It is used to register the relevant extension in more than one place.
In the Features section :
Settings such as call forwarding, follow, do not disturb are made in this tab.
In the Advance section :
RTP, codec selection, register settings and call settings are made in this tab.
