for app there is few users who works with incoming entries.

need functionality:

1) for new incoming entry there is auto-fulfillment of entries (already works)

2) user for assigned to him view can open and edit entries (already works)

3) how can i make access restrictions for  fieldA so that user can open and view inside this fieldA, but can't to edit text of this field ?

example - fieldA is phone field. this field auto fulfilled via web-site. user can open entry and view all data, but he can't edit phone number (text inside this fieldA)