The result was exactly the same. An instant "NO CARRIER".
Instant, huh? Sounds like something isn't waiting for the modem to answer before trying to send more data. Can you post your /etc/chatscripts/provider (or whatever you're using instead) please?
In case it helps, mine goes:
# This chatfile was generated by pppconfig 2.0.5. # Please do not delete any of the comments. Pppconfig needs them. # # ispauth PAP # abortstring ABORT BUSY ABORT 'NO CARRIER' ABORT VOICE ABORT 'NO DIALTONE' ABORT 'NO DIAL TONE' ABORT 'NO ANSWER' # modeminit '' 'ATZ' #OK-AT-OK 'ATW1' # ispnumber OK-AT-OK ATDT08089977001 # ispconnect CONNECT \d\c \r \d\c # prelogin # ispname # isppassword # postlogin # end of pppconfig stuff