Is it possible to assign different SIP accounts to each of the 5 different lines?
Zoiper Classic and Zoiper 3 support more than one account to be registered at the same time. Note that you can have only one active call, all other calls will be put on hold.
Not exactly what I'm asking.. with Zoiper 3, there are five buttons numbered 1, 2, 3, 4, 5. Can I assign a different account to each of the buttons?
I believe you are actually referring to Zoiper Classic.
It has small, blue interface.
Zoiper does not support assigning specific accounts to the lines.