We see two main differences to existing voice applications. First, VoiceGem is meant to be usable by anyone (without having to install an iPhone application, for example). This is the kind of service you can use with your parents, non-tech friends, or customers. Secondly, and maybe even more importantly, we try to enable longer, richer conversations. Whereas blip.me/Voxer focus on walkie-talkie applications (and do a great job!), the messages we get and send are often 5+ minutes long.