We have been requested via social media to shed light on MNP, I gather in light of various dissatisfactions about what all ISPs did in terms of blocking websites in the past few years. Attachment to the number, the costs involved in printing up new business cards, etc were seen by many in the West as a barrier to customers changing from one operator to another.
There are instances when we have unequivocally recommended MNP. But as a general rule, one has to weigh the pros and cons. This slideset is the most comprehensive I could find, though it was worked up for small economies where the economic case for MNP is much harder.
My colleague gives a picture of MNP adoption, that also refers to a decision taken by TRCSL.