After doing what TTT said above,
from your phone you could dial 8LLXX, (LL= line number)(XX=ext number on other system) This would allow you to assign the lines to buttons which do not appear on the exts physical buttons. If you do not have enough buttons.
You could probably also assign the lines to a pool button, and select the line/s in that way, then dial the ext number on the other system.
Make sure to remove the exts from calling groups used for paging, or pages will probably ring in on the other systems lines.
After selecting the line/s you basicly have off hook on intercom on the other system, so any code, you can dial from off hook to intercom on the other system will work. For instance, you could dial a calling group, page, select a specific line on the other system 8LL, dial 9 for outside call, so consider restricting outside calls on the exts you use to run to co/line ports on the other system.
I do not know if there is an intercom code to select a pool group or not, if so, you may be able to create speed dials to select a pool, then call an ext on the other system, or even program a button to do so.
You should be able to test all of this on one system, if you assign say X11 auto line selection to intercom, plug a single pair line cord from line 3 to X11. You can then select line3 from X10 and test how it reacts to different inputs. That response to input should be the same as any response if it was connected to another system.
Do not forget selector code transfers from one AA to an ext that rings at the other systems co line, or even transfering to an ext with outside call forwarding that grabs one of the lines on the system that gets intercom on the other, and dials the ext # instead of an outside telphone number. (This is an R7 ACS feature I believe, and is basicly a conference to an outside line accomplished by a speed dial in the system designating the number to call on the line selected to conference to)
You could also answer a call hit conference, select the line that gets intercom on the other system, dial ext #, then press conference again.
I am not sure how all these interactions would work without testing it, but play with it a bit after you get them connected, and do not say how things will function until you test them.
Sounds like fun on time and materials.
Touch Tone Tommy may have done this on the partner before, I have not, I have done it on dry pairs from the telco between two Toshiba systems a few times before. Speed dials did accomplish many functions in that case, I am not sure how the interactions would go on the Partner ACS though. I think the partner speed dials would select a line as in 8LLXX, but I thik it also sends the 8LL DTMF out after slecting the line, so that may mess up the dialing of an ext on the other system. You will have to play with it.
Let us know how it goes.
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