CallRail is a call tracking and analytics service. Its script swaps the phone numbers shown on a page and stores the visitor's referrer, landing page and session ID, so phone calls and form submissions can be attributed to the marketing source that brought the visitor to the site.
Service URL: www.callrail.com (opens in a new window)
calltrk_session_id
Stores a randomly generated visitor session ID so that a later phone call or form submission can be matched to this visit.
180 days
calltrk_referrer
Stores the referring URL that brought the visitor to the site, so the traffic source of a phone call can be reported.
180 days
calltrk_landing
Stores the first page the visitor landed on, so the page that led to a phone call can be reported.
180 days
calltrk_fcid
Stores a randomly generated form capture ID used to link a submitted form to this visitor session.
180 days
calltrk_override_src
Stores a traffic source supplied in the page URL, used to override the detected source and start a fresh tracking session.
180 days
calltrk_google_experiments
Stores the Google experiment IDs seen on the pages visited, so a phone call can be attributed to a test variant.
180 days
calltrk_nearest_tld
Written briefly to work out the broadest domain that will accept cookies when tracking across subdomains, then removed once that check completes.
3600 days, deleted as soon as the check finishes
Call 559-237-0847 
Text 559-236-6261
