Grasshopper was essentially designed for small offices who want to present a more professionally packaged telecommunications front. Ultimately, though, it's the U.S.-based Grasshopper's simplicity that makes it the winner.
The auto attendant feature automatically redirects an incoming call to an extension without the need of a telephone operator, while audio conferencing lets multiple users join a single call. With ring groups, you can share the distribution of incoming calls among group members. As one of the best virtual phone service solutions, VirtualPBX provides ACD queues, an advanced version of ring groups, among its features. Given that it distributes calls to a group of users, this functionality makes managing a call center with large volumes of inbound calls much easier.

Put some thought into your message before you hit “record.” It takes very little time to write a script for yourself to read as you record your greeting. Reading off a script eliminates unnecessary pauses, “ums” and “ahs.”
That rich feature fabric can change radically between vendors, however. For example, RingCentral's softphone offers a long list of app integrations and features, including not just collaboration platforms, but bi-directional email and scheduling among other things. Line2's softphone client, on the other hand, is specifically designed to be simple so users can pick it up quickly, and it does this by mostly mirroring the buttons you'd find on a standard desktop handset. Two ends of the spectrum, but that means you need to be very careful when testing these apps to make sure you're getting not only what you need but in the right way for how your company does work.