I resolved this before in 1.14.x by adjusting the "Phone Number" field type to short answer in the Contact Information form.
https://forum.osticket.com/d/98542-resolved-new-user-from-ad-invalid-phone-number/3
I have done that in a new install on 1.16.3 and I am still getting a validation error for both Phone Number and Mobile number when creating a new agent, we use 4 digit extension internally and they are being populated in OSTicket by LDAP import.
Can anyone assist?
osTicket Version v1.16.3 (e148727) — Up to date
Web Server Software Microsoft-IIS/10.0
MySQL Version 5.5.65
PHP Version 8.0.0