[Home](./index.md) > [sip.js](./sip.js.md) > [UserAgentOptions](./sip.js.useragentoptions.md) > [hackAllowUnregisteredOptionTags](./sip.js.useragentoptions.hackallowunregisteredoptiontags.md) ## UserAgentOptions.hackAllowUnregisteredOptionTags property > Warning: This API is now obsolete. > > TBD > Hack Signature: ```typescript hackAllowUnregisteredOptionTags?: boolean; ```