Different internal or external rings

There is the possibility of deferring the ringing tones depending on whether the call is from an internal or external?

The version of asterisk is 2.5.0

Depends on the phone model, but there is no asterisk 2.5.0.

I have GRANDSTREAM GXP2100 e GXP2160

so I have to operate on the dialplan?

Yes, You can add a header to either your internal or external calls to notify your users where the call originates.

Look at the PJSIP_HEADER function to add headers.

If you are asking here, it is expected that you wrote the dialplan yourself.

For peer support for FreePBX, use http://community.freepbx.org/

I think this is the same for the Grandstream phones…

same => n,SIPAddHeader(Alert-Info:;info=${ringtone})