[kkielhofner]

You make a good point regarding toll numbers and the real answer is "I don't know" but they persist for whatever reasons...

I'm also not being entirely clear when I say "toll numbers". What I really mean is "high cost" numbers. You're a firewall admin, you know there's no limit to the creativity and ingenuity of scammers/fraudsters/etc with a clear monetization path. There's also traffic pumping[0], jurisdictions where the rate decks overly subsidize the cost to a "mobile" vs "landline", high-rate destinations (like Iridium), and again, various destinations with weird rate structures where (somewhat like traffic pumping) there doesn't seem to be any real justification that the billed rate aligns with the actual cost of delivering service but due to corrupt or non-functioning governments/regulators/telcos/etc they persist and are ripe for fraud.

[0] - https://www.fcc.gov/general/traffic-pumping