Your ping will be getting to the IPO but it doesnt have a route to know how to get back to the remote network.
You will need to add a route to the remote subnet
The gateway on the line form is the IP adress of the remote IPO

Thanks for the quick response GrandmasterOPI. OK, I don't receive a response from the remote IPO (or central IPO, if tried from remote location) because the far end doesn't know how to route the request back to me? How do I program a route to the proper subnet on either remote or central IPO? All through the IP Route fields for each?

You need to configure Network Routes.

EG
Site A Subnet 192.168.42.0/24
Router @ site A 192.168.42.254
Site B Subnet  192.168.60.0/24
Router @ Site B 192.168.60.254

In the IP @ Site A you would configure the following route
IP Address 192.168.60.0
Subnet Mask 255.255.255.0
Gateway 192.168.42.254
LAN 1

In the IP @ Site B you would configure the following route
IP Address 192.168.42.0
Subnet Mask 255.255.255.0
Gateway 192.168.60.254
LAN 1

You can create 16 bit routes which capture 192.168.0.0 you just decrese the subnet mask to 255.255.0.0 = 16 Bit

The reason why this is working now is the Vm Servers all have there gateway address set to the local gateways.

Hope this helps

I see. In the IP routing Gateway field I was entering the remote IP's gateway address, instead of the local router's address. It makes sense now. I'm surprised this isn't covered in Avaya's SCN doc. I guess they assume that IP Route setups are already in place. Thank you both for your timely and concise responses. Will test on Monday.

This works great. Thanks for the clarification on gateways.

A further question - how does an administrator at the central office log into the remote system? Since they're on the same network this should work, no? When they login at the central location and attempt to open a config file, manager searches for available control units but only comes up with the local system. What needs to be done so that they can see the remote configuration?

You need to configure under File/Preferences in Manager the  static address of the remote IPO.

The reason why this is not working is because currently your manager application is set to 255.255.255.255 which is broadcast. Routers will not pass brodcasts. But works OK for your local subnet.

Hope this helps

Super. Thank you.