[Asterisk-Users] Sipura 3000 Call waiting on the PSTN line

[cp]

I have configured my SPA-3000 to direct all calls received over PSTN
interface to Asterisk. That is set up via a dial plan with S0 and works
fine. CID information is passed along as well. But I find it impossible
to setup call waiting on the PSTN line. I do subscribe to this service
from my PSTN provider (SBC). Once a PSTN call comes in, is forwarded to
asterisk and then to a phone at line 1, Sipura seems oblivious to any
other calls coming in on PSTN. When I dial my PSTN number with a second
call I don't see any activity on Sipura. I have set up remote logging
and the level is set to 3. But I still get no activity in the log for
the second call. Even the first call logs very little, but it logs
something. Has anybody been able to get call waiting on the PSTN line? 

Thanks,
Chip