Two accounts (without using Pbxes.org)

[Netsurfer]

Hi,
I have a Xperia Pro and I am very satisfied with this app : )
I have just one question...
If I use two accounts (directly without Pbxes.org), do you mind
telling me how I can switch between these two accounts?
I mean: if I wish to use the first one to receive and the second one
to call... what do I have to do?
If I set the account for the outgoing calls as first, should it work?
I've read somewhere that Sipdroid tries to use both of them when you
call...
So.. I don't know : ) A suffix? A prefix? What can I do?
Please help me!
Thanks in advance...