I'm not the moderator, but I can tell you that I just installed 2 DVG-3104MS PSTN gateways, hoping that I could assign prefix "9" to one gateway (for 4 lines) and prefix "8" to the other gateway (for the other 2 lines we have). Unfortunately, you can't do this. The option is grayed out. It defaults to prefix "9" for BOTH gateways. I understand that if I had installed one PSTN gateway and one digital gateway, then "8" could be assigned to one and "9" to the other. The help files and user manuals are not clear about this because they make it sound like you can select whichever of the two prefixes you want for each voice service. But I believe they meant to say each DIFFERENT TYPE of gateway (voice service) can be assigned either an 8 or a 9.