When using pppd with Linux using chatscripts there is an error with AT commands in establishing the connection because of /d/c not included in the CONNECT string of the chatscript file.
It is always better to use the script file generated by the PPPConfig utility for PPP connection with Linux using chatscripts as there would be problems in connection because sometimes the CONNECT string might not include /d/c while using other script files. The chatscript file generated by PPPConfig might looks as below:
This chatfile was generated by pppconfig 2.3.18.
Please do not delete any of the comments. Pppconfig needs them.
ABORT BUSY ABORT ‘NO CARRIER’ ABORT VOICE ABORT ‘NO DIALTONE’ ABORT ‘NO DIAL TONE’ ABORT ‘NO ANSWER’ ABORT DELAYED
end of pppconfig stuff
connect “/usr/sbin/chat -v -f /etc/chatscripts/airtel”.