Making international calls is different from traditional local calls. To call friends and family in Burundi, you will need to dial your current country code, then the Burundi country code, Local area code in Burundi, and then the phone number you wish to reach.
For example, if you are making a call from the United States to Burundi and you want to call someone in Burundi with the phone number 08035555555;
You will dial the United States country code, 011 and then the Burundi country code plus 8035555555. Alternatively, you can replace the country exit code (011) with (+).