Hi Support, I am new to pjsip. please let me know how to implement below mention solution what I found in same mailing list. Other may have better suggestions but I think one way to modify outgoing messages could be to add a pjsip module that modifies the message before it is printed to the continous buffer. Look in the doc for handling on_tx_request. In the case of the Contact header for pjsua there is a config element that allows you to add extensions to the contact parama. Maybe you could use this as a reference. /** * Additional URI parameters that will be appended in the Contact header * for this account. This will affect the Contact header in all SIP * messages sent on behalf of this account, including but not limited to * REGISTER, INVITE, and SUBCRIBE requests or responses. * * The parameters should be preceeded by semicolon, and all strings must * be properly escaped. Example: * ";my-param=X;another-param=Hi%20there" */ pj_str_t contact_params; /Johan BR Chinthake -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20111004/563ea131/attachment.html>