Conversation so far:
Who was Johnny Cash's first wife?
Johnny Cash's first wife was Vivian Liberto.
Where did Johnny Cash and his first wife, Vivian Liberto meet?
Johnny Cash met 17-year-old Italian-American Vivian Liberto at a roller skating rink in her native San Antonio
Where did Johnny Cash and Vivian Liberto meet?
Johnny Cash met 17-year-old Italian-American Vivian Liberto at a roller skating rink in her native San Antonio
What happened before Johnny Cash's and Vivian Liberto's marriage?
Before marrying Vivian Liberto, Johnny Cash was deployed to Germany for a three-year tour.

Question: How did they stay in contact while he was in Germany?
Self-contained rewrite: How did Johnny Cash and Vivian Liberto stay in contact while Cash was deployed in Germany?