Asterisk: no free channels


I got Asterisk installed with B410p card and i have only two ISDN lines (numbers). I’m connecting the ISDN line to the first port of the B410p board. I’m trying to use the follow me feature in asterisk. To test it out i put two numbers in the followme.conf. If i do not pick up the call at the first number Asterisk is trying to dial the second number. However, it says:

P[ 1] There is no free channel on port (1)

and then forwards the call to voicemail. I have only two ISDN numbers available and i want to call more than one number. I don’t know much about telephony, but isn’t asterisk suppose to use the same channel that was using while dialing the first number? Is there any solution to this or i should apply for more numbers? I really need to make this followme work as my boss needs it done very urgently.

any help will be very much appreciated
Thanks in advance