The Twilio Voice IVR Bridge is a signalling bridge that allows for context to be passed between two voice platforms across the PSTN network. This is achieved by using Twilio Programmable Voice, Twilio Functions, Twilio Sync, and TaskRouter. The bridge is designed to maintain customer call context across a PSTN transfer, ensuring a poor customer experience is avoided. The solution involves creating a bespoke Web Service inside of Twilio Functions that stores the caller's details in a Key Value Store using Twilio Sync. The host platform then calls this Web Service to pass contextual data, which is stored against an available transfer number. When a call is received on this number, the system retrieves the stored data and forwards the call on in context to the application or IVR awaiting this information. This allows for contextual call transfers across the PSTN network where SIP is not available, improving customer experience. The solution also includes error handling, scaling, and cleaning up of transferred numbers to prevent issues with the host platform.