How to subpoena cell phone carriers is one of this blog’s all time most popular posts. As time passes, there are additional considerations to address when issuing the subpoena.
For instance, have you specified the time zone? AT&T responded to a recent subpoena I served by noting, “please include a time-zone in all legal demands served to AT&T. AT&T’s records are kept and provided in UTC. If usage records were requested and no time zone was indicated, AT&T has queried the records in the time zone where your legal demand was issued.” UTC is Coordinated Universal Time, which is also known as GMT or Greenwich Mean Time. In other words, if you look at the records they will appear to be several hours off depending upon the relevant time zone.
Applied to my subpoena, it didn’t matter because the time zone for the subpoena was the same as the local that mattered.