According to the Intercept iMessages leave behind a log of which phone numbers you are poised to contact and Apple will share this with law enforcement when compelled by court order.

Apparently Apple records each query in which your phone calls home to see who’s in the iMessage system and who’s not. This log also includes the date and time when you entered a number, along with your IP address.

All this is the opposite of a 2013 Apple claim that it does not “store data related to customers’ location. ” Apparently Jobs’ Mob is compelled to turn over such information via court orders for systems known as “pen registers” or “trap and trace devices.” Apple fans might think that it is difficult for coppers to get such a court, but apparently it is not that tricky.

Government lawyers only have to prove that they are “likely” to obtain information whose “use is relevant to an ongoing criminal investigation.”

Jobs’ Mob confirmed that month-long log snapshots from Apple could be strung together by police to create a longer list of whose numbers someone has been entering.
Apple said:

When law enforcement presents us with a valid subpoena or court order, we provide the requested information if it is in our possession. Because iMessage is encrypted end-to-end, we do not have access to the contents of those communications. In some cases, we are able to provide data from server logs that are generated from customers accessing certain apps on their devices. We work closely with law enforcement to help them understand what we can provide and make clear these query logs don’t contain the contents of conversations or prove that any communication actually took place.

Andrew Crocker, an attorney with the Electronic Frontier Foundation wondered why Apple was storying this information in the first place.