[Home](./index.md) > [sip.js](./sip.js.md) > [Transport](./sip.js.transport.md) > [protocol](./sip.js.transport.protocol.md) ## Transport.protocol property The transport protocol. Signature: ```typescript readonly protocol: string; ``` ## Remarks Formatted as defined for the Via header sent-protocol transport. https://tools.ietf.org/html/rfc3261\#section-20.42