Number for second channel with isdnctrl

I am using SuSE 9.0 and kinternet (a SuSE tool) to connect to the internet via
ISDN. I have configured several different providers where one is set as default.
When I am connected to the internet, I can use
isdnctrl addlink ippp0
to use the second ISDN channel. I found out that isdnctrl always uses the default
phone number for the second channel which is not necessarily the same used for the
first channel. How can I change this?

Best would be to have the second channel automatically use the same number as the
first channel.
Second best would be to have a little script like this:
NUMBER=012345678
isdnctrl addlink ippp0
How can I do this?

Bernd