>No idea how if your zip codes can start with a zero,
>but that was relatively easy to fix as our zip codes always have 5 digits.
>
>Phone # length on the other hand might range a lot, checking
>for length, area code and "probable mobile code" was challenging.

The probable mobile code may work in Europe - here it's 064, 060, 0677, 064 and such, I've seen 09x in Croatia, and ISTR there were such prefixes in Belgium. In the US, however, the mobile providers have local area codes, so your landline and your mobile have the same area code. Really hard to guess which is which, looking at the number. There's probably some lookup table somewhere, from which you can find that out, but we never bothered, as it's probably changing from year to year and it may also cost some to get, and would require maintenance for... not much of a gain at all.