Don't bother with a 2-line cordless phone, a single-line cordless will suffice. You would program it to access Intercom first, then your 3 lines in any order you chose. When you turn it on, you are on the Intercom, and can dial any other extension. Pressing 9 gives you an outside line. If you program the extension port for immediate ring, you simply turn it on to answer incoming calls. If someone else answers a call and tells you to pick up line 2 (for instance), you turn it on, and on the intercom dial tone dial 6802 to pick up line 2. (6801 for line 1, 6803 for line 3). If you are on a call and want to send the call to another extension, "flash" (usually a labeled button, or pressing the on button again, depending on the cordless phone), which puts the call on system hold, brings you to a stutter intercom dial tone, and then dial the extension number. Either hang up to complete the transfer, or wait until the other extension answers, announce the call, then hang up. You can also "park" a call by flashing, then dialing your own extension number and hanging up. Anyone (including you at the cordless phone) can retrieve the call by pressing Intercom and dialing 6 and the extension number that parked the call.