HL7800 as a network interface in Linux

Hi,
I tried upgrading the firmware to the latest version. Now I am getting this error instead:

pppd[5676]: pppd 2.4.8 started by root, uid 0
chat[5677]: abort on (BUSY)
chat[5677]: abort on (NO CARRIER)
chat[5677]: abort on (VOICE)
chat[5677]: abort on (NO DIALTONE)
chat[5677]: abort on (NO ANSWER)
chat[5677]: abort on (DELAYED)
chat[5677]: timeout set to 10 seconds
chat[5677]: send (AT^M)
chat[5677]: expect (OK)
chat[5677]: AT^M^M
chat[5677]: OK
chat[5677]:  -- got it
chat[5677]: send (AT^M)
chat[5677]: expect (OK)
chat[5677]: ^M
chat[5677]: AT^M^M
chat[5677]: OK
chat[5677]:  -- got it
chat[5677]: send (ATD*99***1#^M)
chat[5677]: expect (CONNECT)
chat[5677]: ^M
chat[5677]: ATD*99***1#^M^M
chat[5677]: CONNECT
chat[5677]:  -- got it
pppd[5676]: Serial connection established.
pppd[5676]: Couldn't set tty to PPP discipline: Invalid argument
pppd[5676]: Exit.