what is it a semi permanent connection?
it is easy!
because permanent connection is a normal bearer channel, ex: Ts or E1. signalling channel and traffic channel is separate. when you borrow a traffic channel to signalling, the channel will be a semi permanent connection. you must config a connetion through ST and dev.
Idle transmission resources in the BSS system being used for carrying data from one to other ,,for example any device need to be connected at BTS side ,that can be configured with dedicated TS in the E1..