The great thing about Bruno being deployed to the Balkans, particularly the City of Sarajevo, was that it shared the same time zone as Berlin. Because of this, he could call his wife that very afternoon, which was a mere few days after leaving her side, and ask for her aid in a matter related to his campaign.
Normally Bruno was not the type of man to share his work with his wife, after all one could consider that a major breach of security protocols. But Heidi's family ties to a Princely family largely involved with military and foreign intelligence allowed him to speak with the woman about such matters.
Even so, Bruno made sure all communications were encrypted before attempting to reach the woman. As a wealthy military family with noble status, Bruno's ability to wire his house in a way to receive and give out encrypted communications via a variety of means was easily established.