I can't make overseas calls

[seka00]

Hi,
 
I have had my Vodafone Blackberry Q10 for 2 weeks and I can't make overseas calls to Dominica. I have successfully called the USA but whenever I try to call any number to Dominica I get this error:
 
'Call Failure
This number is unavailable. Please check the number and try again.'
 
The area code for Dominica is 767 and the number following is 7 digits, e.g. 123-4567. I have tried the following to call abroad:
 
001-767-1234567
 
00-767-1234567
 
0-767-1234567
 
1-767-1234567
 
011-767-1234567
 
and +767-1234567
 
All of these numbers give the same call failure error message. Even when I try to call back a number from Dominica that has just called me I receive the same error.
 
Can anyone help? Could international numbers (excluding USA?) be barred on my phone?

[Serkan B]

Hi Seka00, that's strange. Have you already tried it with a different SIM card? And can you try your SIM card in another device?