In a contact form, I need either their number or email. I've thought of these ways:
- Have field label be "Email or Tel #", or "Email / Tel #"
- Have the above, but placeholder text in the input saying "Either one is fine"
- Have the label be "Contact me by" and then have a dynamic message appear (Twitter style) when the field is put in focus
- Have a select box saying with label "Contact me by" and options "Phone", "Email". When one is selected, an input element below it will be revealed -- respectively Phone and Email
Which, if any, would you consider user-friendly if you were visiting a site?