For a MCS 7825, is it the case if i install a standalone 7825 as Pub, it can only supports 500 IP Phones, but if I install another 7825, each server can handle 1000 ip phones so i get 2,000 IP Phones in total?
When you install it as standalone, you can put 1000 devices on that box.
When you install it as a cluster or 2 servers, both servers share the same database. Still you can only put a 1000 devices in that cluster. But this design will give you more redundancy. If server 1 fails, all 1000 phones will register to the backup.
To achieve some load balancing, you may put 500 phones one server as primary call agent and remaining 500 use the backup server as primary call agent.
For that many number of phones, I would recommend, atleast a 3 node cluster. One publisher and two subscribers.
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.