[Home](./index.md) > [sip.js](./sip.js.md) > [Registerer](./sip.js.registerer.md) > [(constructor)](./sip.js.registerer._constructor_.md) ## Registerer.(constructor) Constructs a new instance of the `Registerer` class. Signature: ```typescript constructor(userAgent: UserAgent, options?: RegistererOptions); ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | userAgent | UserAgent | User agent. See [UserAgent](./sip.js.useragent.md) for details. | | options | RegistererOptions | Options bucket. See [RegistererOptions](./sip.js.registereroptions.md) for details. |