@robertmichell
You can design your own mask, there is a question mark icon next to the "Masked Input" field. Click it to open help where you can read how to do it yourself.
As an example, let's take a typical phone number 7975 556677 - a mask that will work for it will be: 9999 999999
If you need some optional numbers inside, you can wrap it with [] (square brackets). So for example +44 7975 556677 the mask will be [+99] 9999 999999
You can quickly test your mask in the test field that will appear below once you define your mask.
Thank you,
Miro