Asterisk setup for Sipgate and Call1899

Having looked at a variety of ATAs and coming up with a device that
quite does what I want, I've decided to have a go at setting up Asterisk
to:

1. Use an IP phone (IP2006) to make outgoing calls via Call1899
2. Use the IP phone to receive calls via a geographic number provided
by Sipgate

Future requirements:

3. Fit an FXO card (currently a X100 clone) to pass calls to the IP
phone (with CLID)
4. Use the POTS line (via the FXO card) for ougoing calls in the event
of connectivity failure to Call1899
5. Provide an FXS interface to connect a DECT basestation to integrate
my existing (POTS) DECT phones.

Has anyone got any useful config files that I could crib to start me
off?

Thanks in advance!

Peter

Peter Watson