If a stock is truly restricted in the sense of having a restriction in place upon issuance, a mere phone call won't suffice. The restriction has to be lifted under set guidelines which can only be done by the company.
If he restriction was imposed by the broker for some reason, then perhaps all that's needed is a phone call.
You can lead a horse to water. But you can't make him get down on one knee and do an Al Jolson impression!