Hanging Internal Modem.....

[funky]

I'm running REDHAT 9.0 and MANDRAKE 8.1 on my
AMD K6-2 500MHz system. I recently decided to install an internal ISA modem i haven't used in years.
It is the SUPRA EXPRESS 56i SP speakerphone modem and I've got it configured for operation on COM1 port. My external modem is configured for operation on COM2 port and it works fine. Before I did any configuration with KPPP, I ran a couple of modem test using these AT commands as followed below:

1. Test for serial port:

# setserial -bg /dev/ttyS0

/dev/ttyS0 at 0x3f8 (irq=4) is a 16550A

#set serial -bg /dev/ttyS1

/dev/ttyS1 at 0x2f8 (irq=3) is a 16550A

2. Initialization and Reset stage:

# echo -e "ATZ\n" > /dev/ttyS0

3. Volume Adjustment Stage:

# echo -e "ATM1L1\n" > /dev/ttyS0

4. Dial Out Stage

# echo -e "ATDTxxx-xxxx\n" > /dev/ttyS0


5. Termination Stage:

# echo -e "ATH\n" > /dev/ttyS0

The problem with my internal modem occured after the dial out stage. I proceed with the termination stage and the modem remain hanged up in the dial out stage. I'm getting a busy signal flash on my home phone. When I plug out the phone line from the modem line-in jack it disappears and when I reconnect it, the busy line indication appears again on my phone. And yes I do hear a busy signal when I pick up the phone with the modem attached.
.
What the heck is causing the modem to be hung up?

I also tried using this other command CONTROL-C to
terminate the signal. But no luck however.

Is there another command I can use?

Is this a software issue with the modem itself?

THANKS!