[Home](./index.md) > [sip.js](./sip.js.md) > [Body](./sip.js.body.md) > [contentType](./sip.js.body.contenttype.md) ## Body.contentType property The Content-Type header field indicates the media type of the message-body sent to the recipient. The Content-Type header field MUST be present if the body is not empty. If the body is empty, and a Content-Type header field is present, it indicates that the body of the specific type has zero length (for example, an empty audio file). https://tools.ietf.org/html/rfc3261\#section-20.15 Signature: ```typescript contentType: string; ```