A direct route terminates SMS through an agreed connection with the destination operator or its official aggregator, giving reliable delivery, real receipts and honoured sender IDs at the operator's A2P price.
Direct or official routes are the ones operators have sanctioned for application traffic. They cost the operator's A2P rate, which is why they are more expensive than grey alternatives, and they behave predictably: handset receipts where the operator returns them, sender names honoured under the country's rule, throughput as agreed.
"Direct" is a claim that every provider makes. The evidence is in the behaviour over time: stable delivery rates, receipts that match handsets, and incidents that are posted rather than hidden.
At SMSMeteor: route health per region is on the status page with six months of history, and the delivery report names the carrier reason on every failure.