The VG200 can't handle 20 analog loop start telephone lines.
Right now there are no gateways that have a high density of FXO ports (which is the style of port that you need to connect to an analog PSTN line) so the most you could get on a single card is 4. So you would need 5 NM-2V modules, each with a pair of VIC-2FXO style cards, and the only box that will hold that many all in a single chassis is a 3660 series router. Or if you prefer you can purchase 5 VG200 gateways and put 4 ports in each one.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.