Once set-up, just three keys are sufficient to use the High Quality Answering Machine 307 quickly and safely. One key is for “message”, one for “forward” and one key is for “back”. It is not necessary to delete messages as a ring buffer automatically clears the first played message as soon as the memory capacity of 20 played messages is full. In total, the Ergophone 307 comes with a storage capacity of 40 minutes. Typical for well-designed ergonomic devices, the volume can be set to extra loud, the keys are extra large and the writing is clearly legible.