Multiple CIDs that target the same business number (website number) can be grouped together and their tracking numbers be displayed based on the visitor's source of entry to the website (eg paid, organic, Facebook, EDM, etc). As each CID can be setup to track calls based on a specific criteria, it allows for tracking a variation of call sources.
For example, CID 10001, 10002 and 10003 are set up each with their own criteria and each with their own set of rolling numbers. If a call is made and the web traffic matches the criteria of CID 10001 (eg paid), a tracking number from the CID 10001 pool will display. If 10001 is not a match, it will cycle to 10002 (eg Facebook). If 10002 is not a match it will cycle to 10003 (eg EDM) and so on.
If the web traffic does not match any of the criteria, it will not swap in any of the tracking numbers and it will continue to display the client's original website number.
The standard tracking code needs to be slightly altered by adding a "g" after the MID, signifying a CID group follows
<script src="//vxml4.plavxml.com/sited/ref/1000-g-10001-10002-10003" />