A call tracking system and method that estimates a number of calls associated with a publication channel. The system uses a sampling algorithm to perform the estimation. The sampling algorithm selects a group of advertisements to serve as a sample group, and determines a distribution of calls for each of the publication channels associated with the sample group. The distribution of calls from the publication channels is assumed to be the same for all advertisements, and the data from the sample group is used to model the performance across all advertisements. The selected advertisements may be associated with one or more advertisers. Pooled or dynamic signal processing methods may also be used to estimate a number of calls associated with a publication channel. The number of calls associated with a publication channel may be utilized to determine the efficiency of, or calculate the revenue share associated with, an advertising campaign.