[Home](./index.md) > [sip.js](./sip.js.md) > [OutgoingRequestMessageOptions](./sip.js.outgoingrequestmessageoptions.md) > [userAgentString](./sip.js.outgoingrequestmessageoptions.useragentstring.md) ## OutgoingRequestMessageOptions.userAgentString property Signature: ```typescript userAgentString?: string; ```