- VCO can be done over a landline with a VCO phone that displays text, or with a smartphone or computer and an IP (Internet) relay service to place or make the call.
- Either way, the deaf person can speak to the other party and read the person's response as text. The text is provided by a communications assistant.
- Sprint offers an IP relay service with VCO capability and a mobile app for iPhones and select Android phones. Purple's IP-Relay for iPhone and Android works like an instant messaging chat.