Calling home landline from iPhone7

Are you able to call any other numbers? Are you manually calling this number or are you using a contact card that you created? If you are able to call other numbers, try deleting the contact, restart the iPhone, then create the contact again. See if that helps.

If the above doesn’t help, contact your cellular carrier. You phone doesn’t actually know (or care) whether the other end of the call is a cell or land-line. It’s up to the carrier to complete the call.