Partially thaw frozen strawberries, if using. Mash strawberries slightly to break up; set aside.

In a large saucepan, combine sugar and gelatin. Stir in milk. Cook and stir over medium heat until mixture just starts to boil. Remove from heat. Whisk about 1 cup of the hot mixture into beaten eggs; return all to saucepan. Cook and stir for 1 to 2 minutes or until an instant-read thermometer registers 175 degrees F and mixture coats the back of a clean metal spoon. Do not boil. Stir in strawberries, raspberries, and orange juice concentrate. Cover and chill for 4 to 24 hours. (Mixture will be very thick after chilling.)

Transfer the mixture to a 4- or 5-quart ice cream freezer; freeze according to the manufacturer's directions. If desired, ripen. Makes 2 1/2 quarts, 20 (1/2-cup) servings.