When you are using mobile services in roaming and make an outgoing call to a number from a different country than you are in, you must always enter the country code to which the outgoing call is. Example: if you are in roaming and you want to call a Bulgarian number, you must dial +359 and then the number itself.
If you do not specify the country code for the outgoing call, the call might not be reached or even the call can be counted as an added value call that could result in a high bill.
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