depending on the carrier and the level of customers supported -- there is still a decent install base of frame-relay circuits facing customers. the concept of frame is mostly related to l2vpn interworking using atom.
Both of the last 2 T1's I had were Frame. TWTC "Simplici-T" (voice and data) was frame on the T1, but the CPE hands you POTS and (bridged) Ethernet. My speakeasy, then Megapath, T1 was frame, but you we're supposed to access it directly. (I, of course, did because Megapath's hardware was complete shit. And they wouldn't let us use the Speakeasy router.)