Voice over LTE may be just another packet of data in the IP world, but voice services remain uniquely challenging to deploy and will force operators to invest more in infrastructure from base stations to Diameter signalling routers, if they are to deliver a noticeably superior quality of service compared to Skype – which is essential if they are to have any voice-based business case at all. Even the case they have is a thin one. For most carriers it is defensive, enabling them to cling to users who default, out of habit or loyalty, to cellular voice and messaging once they are mobile. Some argue that they will be able to add so many added-value services on top of…