Getting voicemail to work on asterisk for another PBX?

I got the voicemail setup on a macro now in Asterisk. I have one problem though.
If your calling through the Asterisk to say extension 159 on the LG(PBX connected to the asterisk by fxs/fxo signaling), I can set the asterisk to ring for 2 seconds and the asterisk voicemail will catch for it just fine.
If I set it to 3 or more, it will ring then hangup after the set seconds.

What is happening I believe is at 2 seconds, Zap4 (the line I set between the asterisk and LG) does not have time to be answered by the LG so it goes to the appropriate DIALSTATUS in the macro (NOANSWER) and catches the voicemail.
But, at more then 3 seconds, the LG Answers the call, (although the user at that EXTEN did not answer it yet on the LG) so the macro quits because it thinks it was answered and will not continue into voicemail (NOANSWER, BUSY, etc)

Got any idea how to get around this? (one other thing, it does go ahead and hangup my call on the asterisk after the set amount of time if the LG extension is unanswered…)