Hey, Ken. The ITT601 was ready to go for five lines AND they had a plug-in 10-station intercom card that plugged in the bottom slot. All that was needed was the appropriate number of line cards. Of course, if Touch Tone intercom was desired, a piggyback card was required. The 601 had all of the regular power connections available if you wanted to use an external intercom, like a Melco or Tone Commander unit.
