You haven't watched any of the Bill Binney interviews, have you. He addressed your hypothesis in them and excluded it because the time between the files excludes a telephony link of any type, other than military, which the DNC never had! His analysis is that it had to have been a thumb drive or similar. The header & footer + error correction required for Ethernet and any telephony methods puts in a small but noticeable and measurable delay. His observation was that the time gap is too short for packets to have delivered the data!