A computer implemented method is provided for tracking user activity across different communication networks; the method comprises receiving by a receiving device accessible on a first network, such as the internet, a request from a requesting network device, for an address on a second network, such as a telephone network or an SMS network; receiving by the receiving device from the requesting network device a combination of one or more attributes indicative of a source, such as an ad campaign, web location or keyword, that can lead a user to send a request for information over the first network; selecting a pool of addresses an addresses that is accessible on the second network; producing an association in a database between the selected address and the received attribute; and sending the selected address to the requesting network device over the first network.