Tier-1 without their own backbone?

[Rick Ernst <erond () legendz com>]

We are sending out feelers for adding an additional DS-3, or possibly frac
OC-3.  One of the responses came back with "we won't be competive with
<provider> because they don't have their own backbone.

Is there a cross-reference for provider vs network backbone, or is this just
something that we have to ask each provider for?  I "assume" that UU, Sprint,
and AT&T are self-owned backbones, but others... ?

One of the providers we are looking at is Level-3.  Any comments good/bad on
reliability and clue?  We already have UU, Sprint, and AT&T.  I also realize
that the "they suck less" list changes continuously... :)

Thanks,
Rick