No, it can not.
One account ID can not sign in on two or more computers at the same time, if you sign in on another computer, and it will be forced to exit on the computer that the account signed in. While two or more accounts can sign in on one computer.

There maybe some of the reasons bellow:
1. You do not sign in.
2. Check the security level of your browser, if the security level is too high; please return to the default settings.
3. Stone Messenger downloaded incompletely, and no related info in the registry. Please quit all the systems which have the registry monitor, (for example: Rising anti-virus software and other same systems), and download Stone Messenger again.

Each account can have 500 contacts, can create 1 group, and can join in 10 groups.
Each group can have 100 members (accounts), can have 2 administrators. The group owner has the upmost right, he can name the administrators, can also delete the group. Only the group owner and the administrators have the right to invite others to join the group.

First click Video Meeting Room on the Stone Messenger; second choose the meeting room you want to join in; third click Join. After that you are in the meeting room, and can start your chat or speech.

After registering as a member of Stone Messenger the system will automatically offer you the one and only series no., you can check it from "my card" on Stone Messenger.

Yes, it does.
Stone Messenger offers the whole complete system for the members of www.stonebtb.com. All the members can sign in and contact directly on line with other members or their customers and potential customers.