I have a Panasonic KX-NCP500 here with a virtual SIP trunk to another PBX. I'm trying to program it so I can make a trunk group and assign it to the SIP channel. For example I can dial 8 then the trunk group then the external PBX extension number IE 802204( Meaning the 204 is the extension I'm trying to reach) I'm not sure if I am asking the correct question to accomplish this task as I am new to the Panasonic systems. Thanks!

If you use other pbx and put 2 as lead numbers as long as it is not used on your local system then put 2 in private network pointed to sip trunk group

If 2 is in use on the system you can add or remove digits

So the Panasonic system has extensions 102-105
The Asterisk(FreePbx) has extensions 201-206
I went to 9.Private Network under System Menu in Maintenance Console and under 2 I changed the Trunk Group to 2. Didn't change Removed Number of Digits or Added Number. Tested and it still does the same thing.
However I may have my trunk group improperly setup. I will double check that.