How do I classify a phone number as mobile?

A person's phone number can be classified in several ways:

work
personal
other

And by Type:

mobile
voice
fax
other

If the SMS icon is grayed out on a person's Cloze profile it means that their number is not classified as mobile. You can edit the profile and classify it as mobile.

1.) Tap on the contact you want to make a change to and then tap on "Edit".

2.) Tap on "Contact info" and then scroll down to their phone numbers.

a.) If you see a label called "Mobile" then that number has been classified as a mobile number.

Under Contact info, look under Phone Numbers for a Mobile label and icon.

b.) If there is no label called "Mobile" (this example shows "Voice"), tap on the device icon and select "Mobile".

Tap the first icon on the right to set the Type.

3.) Tap Save in the upper-right to save your changes.