Hi Nicolas One way to accomplish this could be to use a media transport adapter, there you can modify the rtp packets before they are sent down to the UDP transport. Unless you can guarantee that the bytes before the original header are available you would have to copy the whole payload to a new buffer and will be quite inefficient. For a simple trial you can probably use this approach but for a commercial product you might want to look for better suggestions. I have not looked into the code but since pjsip at least documents this extension maybe there is a way to activate this support or to make a simple patch that always adds your extension header when building the rtp header. BR Johan ________________________________ Este mensaje se dirige exclusivamente a su destinatario. Puede consultar nuestra pol?tica de env?o y recepci?n de correo electr?nico en el enlace situado m?s abajo. This message is intended exclusively for its addressee. We only send and receive email on the basis of the terms set out at http://www.tid.es/ES/PAGINAS/disclaimer.aspx -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20120731/267cb4b1/attachment-0001.html>