Possibly Trans World Systems, a debt collection agency. Have received other calls from Trans World in the past from various 314 area code numbers as well as 800 numbers. Many times when these phone calls are answered you will be placed on hold via machine, assaulted with beeps, sequels, dial tones or various electronic noise. While it's nice they're trying to make supposed debt ridden 'clients' important with the whole alien signal spoof... it makes the calls pointless.
At least give me someone to yell at after you make my bad day worse by adding the annoyance of a ringing phone to it. Then at least your phone calls would have a purpose.