Everything worth knowing, nothing that isn't.
Why MNP is messy for SMS
If you assume a number's prefix tells you the operator, you are wrong about 5–25% of the time depending on the market. In the UAE the ported share is ~12%, in KSA closer to 18%, in Egypt ~9%. Send to the wrong operator and the message dead-letters, or worse, gets rerouted through inefficient operator-to-operator interconnect that the originator pays for at a higher rate.
How operators expose MNP data
Centralised number portability databases (CNPD) in some markets (UK, Singapore, India), per-operator portability flags in others. SS7-based lookup is universal: an HLR query returns the current serving operator regardless of original prefix. BroadNet's HLR Lookup API normalises across both models and returns `currentOperator` and `originalOperator` as discrete fields.
What MNP means for sender-ID compliance
Sender-ID registrations are usually per-operator, per-country. If your sender ID is approved with STC but a recipient has ported from STC to Mobily, the message now needs Mobily's approval too. Mature aggregators register sender IDs with all operators in a country. Less mature ones quietly fail the cross-operator messages and tell you nothing.
Practical recommendation
Run HLR Lookup on every new number at acquisition time, and re-scrub your active list quarterly. The cost is fractional compared to the SMS sent to dead-routed numbers, and your DLR success rate improves because fewer messages go to dead numbers.