Hello pt1989,
If your wireless carrier supports Dial Assist, you don't need to enter “+” before an international phone number. To check for that, go to Settings > Phone > Dial Assist.
Turn on Dial Assist for international calls: (GSM) When Dial Assist is turned on, iPhone automatically adds the correct international or local prefix when you call your contacts and favorites.
For information about making international calls (including rates and other charges that may apply), contact your carrier.
If Dial Assist isn't an option for you, you can add a “+” for international calls in your Contacts.
Enter a “+” for international calls: Touch and hold the “0” key until “+” appears.
You'll find this information here: Make a call on iPhone
Take care!