The IP information is a common and general location, usually of your nearest Telecom tower. IP address in itself does not lead to your Internet device. So the paragraph is still inaccurate if the Ad agency is tracking through IP. Your IP was always naked and available to anyone you send email to (through the headers).
But your actual IP address still does not tell them your precise location. Unless they also separately get a log of what cell tower handled traffic for what IP addresses, they'd still be left with only the location of your local internet provider.
I might have been mislead by the use of IP, the handset is what is tracked and it usually is more precise than just what tower the device is associated with. It can include measurements taken from multiple towers, which can be derived from data needed for CDMA to even function, or it can include government mandated E911 information which is usually derived from an internal 4-channel GPS receiver. In theory this is only supposed to be used for E911 functions when the handset is in contact with a PSAP, but we have no way as the public to know what information from these systems are collected and stored or for how long.
An IP on a mobile device is not as same as an IP on desktop. As far as desktop is concerned, unless ISPs are willing to track your exact location for the government, there is no way anyone can pinpoint your exact location through the public IP address.
