Employing a comprehensive call routing system is essential for a network with multiple carriers. Call routing solutions from IPtelX not only provide traditional least cost routing (LCR) functionality, but can also route according to other criteria, including call quality using measurements like mean opinion scores (MOS), session initiation protocol (SIP) response codes, Post dial delay (PDD), packet loss, or jitter. Few call routing engines analyze data within the call stream to perfect the call quality a client is receiving. In addition, IPtelX can provide custom interfacing with other software or systems through its API, which could allow customer-provided data to affect the call routing decisions.