As a host, it would be handy to search guests by phone number. I am usually contacted by text message, and although I've had nothing but great guests, sometimes I would like to check their profile so I know who I'm expecting. I can usually track the guest down by name and location, but many only give their name. Maybe this is already and option and I overlooked it, but I know it would certainly help.
Not on Front Page
Very few directory services allow reverse lookup of phone numbers. And a guest may not have phoned from his own phone.
I think it is best to ask anyboody phoning to send a message on the site. That way you can look at feedback before committing yourself, and of course have confidence just who it was phong you.
From experience, best also to ask guests to confirm that they will be arriving and leaving by bicycle.