Where's 209.240.157.34 ?

Richard Parker wrote:

Perhaps ARIN has reserved the entire /19 for TierraNet, but only
actually allocated the lower /20 to them? Perhaps TierraNet is
announcing their /20 as a /19 to get past Sprint's route filters?

That is what ARIN has been doing. Those who qualify for /20 can
get a /20 where they can eventually get a /19 so that they can
announce as /19 to bypass Sprint's discrimination against small
businesses.