Carrier PoP equipment not UPS backed?

My question for the community is regarding expectations of the presence -- or lack thereof -- of a UPS backing carrier equipment in a commercial building PoP.

I recently had an incident where we lost two circuits during a "carrier equipment power failure" as stated by my carrier, Lumen (aka CenturyLink). We have two metro ethernet circuits terminating on a typical Ciena carrier switch that I know has been in service for no more than about 18 months. I was told this switch is not backed by a UPS.

I've seen this equipment personally, but never paid much attention to where the power went. It's located in the primary telecom room in a multi-story commercial building with other tenants and a mix of legacy and newer equipment from various carriers.

I've been doing network engineering for well over a decade, and I apparently made the incorrect assumption that carrier equipment in these situations was typically backed by a UPS. If the carrier equipment is in our IDF, I expect to connect this to our own UPS. As a further point, we are not the sole customer connected to this Ciena switch. I believe there's one other active circuit there last I saw it.

Making sure our own equipment is UPS backed and redundant only to find out I have a simple power failure point during a brown-out due to our carrier's lack of power conditioning is frustrating. They've suggested that I can ask an account manager to request adding a UPS for this switch, or I can add my own according to the tech I talked to.

Thoughts about which way to go? If I ask Lumen to do it will probably take months, and they may even tell me to go pound sand because it's not required/supported. If they let me add my own, that means I'm now responsible for it, and another business in this building is now reliant on our maintenance of this UPS. I can't even begin to speculate on the legal ramifications of this, nor can I believe Lumen would be okay with shared equipment relying on something they don't own when more than one customer is dependent on it. Yet that's one of the options they've offered.

Anyone have experience here? Much appreciated.