How distinctive are your ticket IDs? If they are distinctive enough, then you could write a Moodle text filter, so that wherever someone types a ticket id, it is automatically made into a link. That is just like if you type "MDL - some number" in these forums, which is what Moodle tracker issue ids look like, then you automatically get a link like MDL-3030.
If you have that filter in place, then you can just use the ordinarly Online text assignement (or the equivalent in Moodle 2.3+), but it will also work in other places. For example, if you had a discussion forum, then it would be easy for people to discuss example tickets there.