Can check-in staff make changes to reservations?
 

I have this question because when someone notices some mistake on his/her booking, many times one phones the airline and they issue an OSI which tells check-in people "please change whatever on the passenger info". I just thought that why do they issue the OSI instead of changing it themselves:confused:

Depends on what kind of change...but, I suspect most changes require some form of id verification from the passenger. Anyone can pick up a phone and try and change your itinerary or name or whatever on your PNR. There are probably security reasons for the need to have someone physically verify your identity and make the change in person.
-L

Making an actual change in a reservation - such as correcting the spelling of a name - requires that a ticket be reissued. Putting an OSI in a reservation does not require reticketing. So if your name is misspelled and doesn't match your ID exactly, the simplest thing to do is just put an OSI in the reservation so that the check-in agent is aware of the discrepancy and allows you to check-in under the misspelled name. That is a lot simpler than having to reissue the ticket.