That's lovely, but once you've remembered it?

I'm never going to forget my mobile number, I don't need to keep calling myself to remember it.

But the reason you don't forget it is probably because you recall it all the time. You definitely recall your phone number for purposes other than calling yourself.

This has given me a good idea for a study: find people who have changed phone numbers and see how many of those people can remember them. Then plot the data by the last time they used that number.

Anecdotal but I for one have been using grand Central/Google voice as the number I share with others since about 2008 and I don't remember any of the numbers I've used for the actual cellular carrier.