Ascom d63. Quite possibly the world’s hardest working handset.Wideband audio—the Ascom d63 advantage. The Ascom d63 features ‘wideband audio’, extended bandwidth of 50Hz – 7,000Hz that delivers exceptional sound quality that goes beyond traditional telephony. And it’s backward compatible, achieving outstanding sound quality even when communicating with conventional devices. The Ascom d63 — voice quality you’re sure to hear about.