[Home](./index.md) > [sip.js](./sip.js.md) > [InvitationProgressOptions](./sip.js.invitationprogressoptions.md) > [extraHeaders](./sip.js.invitationprogressoptions.extraheaders.md) ## InvitationProgressOptions.extraHeaders property Array of extra headers added to the response. Signature: ```typescript extraHeaders?: Array; ```