The MOBILE PHONE/HOME PHONE/WORK PHONE fields in ARMS will allow you to type in the 10 digit US phone number (###-###-####) to save.
If a phone number is more/less than 10 digits or containing any letters, the phone number will not be saved.
What we recommend doing is CREATING A CUSTOM FIELD to hold on that profile. The article in the hyperlink above will list out instructions for you to create an "International Phone Number" custom field. This can be made for Recruits or Student-Athletes and is a good way to hold the more/less than 10 digit alphabetized phone numbers in ARMS.
When creating the field select the TYPE of Textbox. This will give you the ability to type whatever you would like in the field (numbers, letter, Country of origin, etc.)