Who can?
All of the law enforcement agencies and probalby some others too.
All yankee government police can get a subpoena for records. In Georgia, local law enforcement has to have a warrant to get phone records and almost everything else. Except bank records, local law enforcement can still get bank records w/o court order.
Up until about 20 years ago local cops did the same thing as the yankee government police do, but the Georgia Supreme Court said it wasn't legal. What they'd do is get a subpoena for those records to be sent to the grand jury. But in lieu of taking it directly to the grand jury, it could be sent to Detective So-and-so. Georgia SC said that wasn't legal.
Because the yankee government does so much of its investigating through a grand jury anyway, it still does this (though I don't know that it's ever been tested with SCOTUS, but one would certainly presume so).
In a major case that you're familiar with where the local cops worked with the yankee police, they found it was faster and easier to get a judge to sign a warrant than to seek records on subpoena through the yankee bureaucracy.