[Home](./index.md) > [sip.js](./sip.js.md) > [UserAgentOptions](./sip.js.useragentoptions.md) > [userAgentString](./sip.js.useragentoptions.useragentstring.md) ## UserAgentOptions.userAgentString property User agent string used in the UserAgent header. Signature: ```typescript userAgentString?: string; ```