Look for the following features:
- Voice quality is good and loud enough; no echoes
- Speaker phone capabilities; again no echoes
- 3 way conference call capability
- Speed dial – that works well!
- Readable LED display
- Documentation should be easy to read and understand
- Efficient operation (i.e. not slow)
- User-unfriendly web page
- Fair price for value
- Good looks for good quality phone (i.e. no poorly-built, cheap buttons that you need to hit with hammer to activate)
- Equipment works with firewall intact
- Good configuration, functionality, stability, and codec support (for example, it shouldn’t need constant rebooting or maintenance)
This is from a website known as Free VoIP Tips.