First you'll need to make your phone number on your profile visible to the people you choose (but it sounds like you've already done this).
On the desktop, those people will be able to see your number on your profile, in Google Contacts, and in Gmail.
On their Android phones, they'll be able to see your number in the phone's address book, provided they have the Google+ mobile app installed and they've turned on sync from Google+ to the phone.
And on both Android and iOS, they'll be able to see your latest number in the Google+ mobile app.
Hope that helps!+David Prieto