Creating contact from recent call

You'll also want to verify that you have Contacts turned on for the accounts in which you'd like to be using, as shown here:

Manage and delete contacts on your iPhone, iPad, or iPod touch

Once you've verified the settings are all correct, then add a new contact and then verify that it saved.

Add and use contact information on iPhone

Hello:) Check this out and see if it helps.

1. After you finish a conversation, tap Phone→Recents. ... 
2. Tap the Info button to the right of the number you want to add, it can be from a callyou received or one you initiated. ... 
3. Tap Create New Contact. ... 
4. Tap Add to Existing Contact.

Hello again:) Not knowing what you have tried …take a look at this as well.