xapo is making all out effort to get in first of all, I used them before, there is no problem, except the phone verification, the main advantage of btc is anonymous, but the xapo is killing the advantage with verification...
Pretty sure other wallet/storage services like Coinbase and BitGo make you put in a phone number as well, maybe at later stages in the account, but I think they still require it
Actually, you can also add it to Blockchain.info. Granted, it's not required, but still...