Communications Among Cultures

I've been working with a woman in the South while doing my small part to plan my wedding. She's very nice and very helpful, but she prefers to communicate over the phone instead of by email. The first time she called me, I answered twice and she hung up right away. The poor woman couldn't understand anything I was saying and assumed that she had the wrong number. I've since changed my phone number, and today she sent me an email (for the first time) saying that she'd called my old number a couple times and left messages, but someone named Rosalio called back to say she had the wrong number. We got on the phone finally and proceeded to go down my list and hammer out a few important details. At the end we recapped and everything was perfect. Then her assistant sent me the updated invoice and everything was wrong. The issue isn't one of competence, it's a linguistic divide that we're having trouble bridging. At this point I just hope we have the date right.