No, the assumption of the design seems to be that the sysadmin will send the ring only to the phones that will answer the call. when you pick up a ringing phone it will answer the line on the phone that has been ringing longest. If you tap the intercom first then pickup the handset then you will have intercom dial tone. if you tap one of the line buttons first then pick up the handset then you will have CO dial tone. If you just pickup the handset when it is ringing then you will be talking to the ringing line.
If you do not want to have a phone answer ringing calls set the line appearance to appear only.
If you have an overhead paging you could set the lines to trip an overhead bell/pa and then the calls could be answered by the phones manually, but with just a phone system you have to turn the ring off in order to not answer it.
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'Rule 29', "The enemy of my enemy is my enemy's enemy. No more. No less."
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JerryReeve
Communication Systems Int'l
com-sys.com