You certainly can change Website via a webhook. It's a standard data enrichment target.
Make sure it's not set to block field updates from webhooks.
Note Website is a Company field, not a Person/Lead field, so the standard expectations apply.
Use Twilio's Lookup API Validation and Formatting endpoint for that. Follow the same directions as in Calling the Twilio Lookup API as a Marketo webhook.
Or you can embed Google's libphonenumber SDK in any supported language.
I've personally written one for Australian phone numbers but not sure if that's any use to you. Global numbers are too hard to manage so paying for service might the way to go if you handle data from various countries. The logic and code is a lot more full on for a phone number formatter than separating domains though...
The logic and code is a lot more full on for a phone number formatter than separating domains though...
Yep, that's why there's a whole library for it (Twilio themselves uses libphonenumber, since they didn't feel like they could do better in-house).