5 beeps without a pause is invalid. Perhaps it was some beeps, a pause, and some more beeps to total 5? The recording "sorry, your call can not be completed as dialed" is from the phone company, because you're dialing a series of the digit 1. Try calling your cell phone, and now that the line is connected and clear, do the Feature #1
Partner Basic does not have calling groups, so that's out.
Partner Plus R1, R2, and R3, and Partner II R1, R2, and R3 do not have the 4 calling groups, only 1 is available, so that's probably what you're dealing with.
Beep codes for these systems are:
2 beeps = Partner Plus R1
4 beeps = Partner Plus R2
2 beeps, pause, 4 beeps = Partner Plus R3.0
2 beeps, pause, 2 beeps, pause, 1 beep = Partner II R1
2 beeps, pause, 2 beeps = Partner II R2
3 beeps, pause, 1 beep = Partner II R3.0
In this case, dial #502, then the extension number, then 1 to assign to the group.
Intercom *71 will page the group
*70 is Simultaneous Page, which pages all of the phones in Calling Group 1 AND the loudspeaker page port.
It was introduced on Partner II R4.0, and all of the ACS line. Not available on any release of Partner Plus