Legacy PBX wants to get Asterisk's co trunk line

Hello All,

I am running AsteriskNow 1.7.10 + FreePBX 2.7.0.10

I need users in legacy PBX systems (NEC NEAX) would be able to get Asterisk CO Trunk…
hmm … any tips for doing this?

please advise

Thanks & Regards
Winanjaya