Question about phone verification

Can I use just one phone number to verify accounts?

As in:
1. Verify accountX with PhoneNumberY
2. Remove phone number from accountX
3. Verify accountZ with PhoneNumberY
4. Remove phone number from accountY
5. Repeat

I understand that removing the phone number eventually beats the purpose but its just to remove the lock imposed on some accounts.

It's ideal to use separate numbers.

You can do it like that but its better using more then just the same phone number. This way if twitter account 1 gets banned for spam or whatever the case is it won't be likely that your other twitter accounts will go with the first account.