[Home](./index.md) > [sip.js](./sip.js.md) > [UserAgentCoreConfiguration](./sip.js.useragentcoreconfiguration.md) > [userAgentHeaderFieldValue](./sip.js.useragentcoreconfiguration.useragentheaderfieldvalue.md) ## UserAgentCoreConfiguration.userAgentHeaderFieldValue property User-Agent header field value. Signature: ```typescript userAgentHeaderFieldValue: string | undefined; ``` ## Remarks https://tools.ietf.org/html/rfc3261\#section-20.41