To quote my boss, you are the solution, not the problem.
The signage referred to here is an attempt by the city to make the system a little safer. The signage tells the occupants of the building, when fleeing for their lives, to take one more step to call the fire department because the fire alarm system doesn't do it itself. See The Sign Said to Call 911
to get my opinion as to how good the signs are.
The NFPA Code and how it relates to the city, the owner, and the fire alarm system installer/servicer needs to be understood. In all of this, keep in mind that the owner owns the fire alarm system, and not you. If the city is requiring upgrades to the system, the city is requiring owners to upgrade. Your job is to help the owner keep up with city requirements.
NFPA Code is not code, it is not law, it is not an absolute. It is a bunch of words written on some paper published in a book giving suggestions on what to do to make buildings safe. Most city, county, state, and federal agencies take these suggestions and say this is going to be law.
In addition, the governing bodies often add to the "Code", subtract from the "Code", or change the "Code". This explains how the city can require signs be installed by the owner. Remember, it's the local government that's the law, not the NFPA.
Sometimes the city governments will decide that everyone should be brought up to the current "Code". A way of triggering the required upgrades is that when the fire alarm panel is replaced, even with an exact same model, the whole system needs to be upgraded.
Remember, as far as the fire alarm system goes, complying with city law is the owners responsibility. Helping the owner comply is something you can do. The problem is the city, the solution is you.