DT famously does not use them. They prefer to shut down their peers to make them become customers or fuck off, and by doing so, deliver crappy service to everyone and lose customers, except they have a monopoly so they don't lose as many customers as they should.

We have many BGP workarounds to avoid interconnection points with some of our tier 1 providers and DT because as our providers tell us, discussions with DT to add capacity are a non-starter. We've been relatively stable through a tier 2 provider through Lumen to DT though... for now. Very similar to Cogent in some regions.