I've recently changed my setting on my Nokia N8 phone from dual mode (GSM & 3G) to 3G mode and found a improvement on my calls with my girlfriend. We both use the plantronics 975, my phone is an Nokia N8 and her's is an Nokia C7. I've noticed that her voice doesn't sound as muffled as it did before. I've read elsewhere that 3g does improve voice quality (http://www.gsmarena.com/orange_launc...-news-1118.php). It's probably common knowledge, but this may come as new news to some.