Adtran n00b here. Will be using an Adtran to hand off from a SIP trunk to POTS on a PBX. From my experience with other hardware manufacturers, this needs to be done with an FXO port, but from what i can tell, the Adtran TA 900's cant do more than a couple FXO lines (I think I saw the 924 can do up to 8 FXOs). If i need to hand off, say 16 POTS to a PBX, what Adtran device can I use to get 16 FXO ports on? or will FXS ports work?