Call Forwarding between extension but not on voicemail

My customer want to be able to setup a call forward between 2 extensions but if the second extension dont answer the voicemail must be the voicemail of the first extension.

I could not find this option in freepbx but my customer have it before on a very old nortel system.

Schema to be sure everybody understand:
Call to extension 100 ----- Forward to extension 200 ---- 200 dont answer go to voicemail of extension 100.

Maybe its easy and I just forget something?
Thanks in advance!

This can be done easily using Follow Me.

. . . and for a complete “mimic” of the old nortel behavior turn on DND on 100 if it as available.

I explore the Follow Me option, but maybe my first answer was not clear enough, but the forward extension can change day to day, and the user dont want to used the UCP to change followme setting.