If SMS messaging is a channel you use, there's a good chance you've thought about or tackled how to standardise phone numbers so SMS just... works.
As for me, I wrote a script to do it in bulk, and added in a little bit of data enrichment while I was at it.
Check out the bulk cleansing tool here - remember Australian phone numbers only!
Eventually I turned to calling a webhook whenever phone numbers were changed or when a person was created so I didn't have to manually clean phone numbers before every SMS blast. Unfortunately this is an entry level web server and it just isn't reliable enough to perform a high throughput of requests so I can't make that available here, but if you'd like to set up something similar, reach out.