Hey guys
let's take a step back and compare apples to apples
Large installations on hosted make not a lot of sense because you are relying on the Internet connection to make the phones work. Your Internet as well as the providers Internet and all between connections. If you have 10 locations with only 3-10 phones each it makes much more sense because you don't need hardware other than phones in each location. It is unlikely that all your locations lose Internet at the same time (except if the provider is the same) so you should be able to get the calls.
If you want real redundancy you have to spend a lot of money to have that on a local level.
Redundancy is a great thing and advertised by a lot of hosted providers but
they also must have redundancy and not just claim that this is a feature and they usually charge more than providers without that ability.
I am old school and have my own phone system (Avaya IP Office) at home with SIP and analog trunks (yes analog

Alexander Graham Bell is proud of me) if my phone system goes down (I have 2 backup systems that I just need to plug in and I am up and running but that is not the norm I guess) the SIP gets routed to my cell phone when not connected and the analog trunk is never used other than by telemarketers and outgoing
Hosted and on-prem systems have their advantages and they are not in the same ranges so I don't understand the pissing match about which one is better all the time.
Take the ruler away and say that each customer has a unique requirement and therefore each customer may or may not be best served with hosted or on-prem systems.
One thing I have to however clarify: hosted phones, even though they are SIP, may not work on ALL other hosted solutions as well as they do on the one they worked at one time. Even SIP phones have compatibility issues and sometimes to make them work it is just not worth the amount of labour to figure out which settings need to be tweaked.
Joe W.
FHandw, ACSS (SME)
"This is the end of the world, make sure to buy your T-shirt before it is too late"
Original expression of my daughter