Maintanance testing

Hello everyone,

Does anyone know more info about maintanance testing,i need to know who is responsible for it and any processes that can be followed. if a team is responsible for testing for example a billing system and they only test new requirements which are not too many then do regression testing on the system.and then again responsible for re-testing defects that are raised in production, is there a process that this team can follow?:confused:

right now it feels like this team is doing fire fighting testing :mad: so any help will be highly appreciated.:):)