Edit the etc/asterisk/extensions.conf

I have tried to modify the file and I am unsuccessful in accessing. From the CLI I have tried sudo vi su vi and accessing the directory directly. I am unable to access and edit.

DId you include the first / in the path name?

If so, this is a Unix/Linux question, not an Asterisk one.

Yes sir I did.
I tried the Su vi /etc/asterisk/extensions.conf
I was hoping that not to be the case.

Does the file exist?

The file exists, but is empty. There is another extension_corporate. Configured

I had to cd /etc/asterisk
Comes back
/etc/asterisk$ I can do a dir and see the files
From there I do a vi extensions. Conf and the file shows empty exit
Do the same command with extensions_corporate.conf and it has the dns and routing.

Your issues seem to relate to local configuration performed by someone else. We can’t easily guess what they have done. You need Unix/Linux knowledge to understand this, much more than Asterisk knowledge.