ipp "<sip:sipp@9.13.24.7>;party=calling;screen=no;privacy=off II From: "sipp"<sip:gateway@9.13.24.7>;tag=1EDB2D94-11DD continues 122 SIP Trunking Example 7-5 Normalized SIP INVITE (continued) To: <sip 2222000020@9. 13.32.240 context=gateway> Date: Thu, 30 Aug 2007 07:04:36 GMT Digit Manipulation Another technique to suppress or change nonpublic numbers from exiting your network is to use digit manipulation techniques at the border of your network. For example, a non-DID number can be changed to your organization's basic public PSTN number if the call should go off-net. SIP Privacy Methods Various SIP specifications control the privacy of end user information in SIP messaging such that numbers and names can travel in the messaging but still be suppressed from delivery or display to the destination endpoint. Similar methods exist in ISDN when inter- connecting to the traditional PSTN. SIP specifications (and CUBE capabilities) of interest in this area include The Privacy SIP header (RFC-3323) provides guidelines for withholding the identity of a person (and related personal information) from one or more parties in an ex- change of SIP communications. The P-Asserted-Identity (PAI) and P-Preferred-Identity (PPI) (RFC-3325) headers pro- vide extensions that enable the communication of the identity of authenticated users and the application of existing SIP privacy mechanisms to communicating these identities. If your applications are not SIP-capable, or if they do not insert these headers, you can have your border element insert (or change) the content of these headers as a call leaves your premises over the SIP trunk. The CUBE can also convert between the widely deployed Remote-Party-ID (RPID) header to and from PAI/PPI and Privacy headers. Registration and Authentication You can use SIP mechanisms to validate the originator of a SIP call and therefore provide a mechanism to reject SIP INVITES that come from rogue endpoints. These mechanisms include Registration: Some service provider SIP trunk offerings include a reg