How to customise the activities status?
From the administer dashboard, you can modify the option groups:

civicrm/admin/options?reset=1

and the activity status is one of them (/civicrm/admin/options?gid=26&amp;reset=1 in my case).

However, there is a big 

 WARNING: Many option groups are used programatically and values should be added or modified with caution.



Left Message
Unreachable
Available
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Are not reserved (ie. we can delete them)

Is this safe to do so? can I add new statues without issue?