search for: hiarpinning

So I have an application where the users want to divert incoming calls on one analogue line out to another analogue line - both lines are supplied by BT and theres a TDM400 in the box. Call comes in, system Dial's the forwarding number and bridges the calls. Works fine. Until one (or both) leg hangs up. And the box never sees the hangup. So it sits there with both Zap channels open