LinuxQuestions.org - Huawei E1731 doesn't dial successfully

I'm trying to setup Huawei E1731 USB Modem in LFS system, but it doesn't dial successfully. The Card has switched from storage to modem mode. I have configuration files(chat script, options file) and debug logs below for anyone to help me. Thanks

lsusb output:
-------------
Bus 002 Device 003: ID 12d1:1436 Huawei Technologies Co., Ltd.

pppd's options file output:
---------------------------
lcp-echo-failure 1
lcp-echo-interval 1
/dev/ttyUSB0
115200
debug
defaultroute
ipcp-max-failure 4
ipcp-accept-local
ipcp-accept-remote
noipdefault
novj
nobsdcomp
novjccomp
nopcomp
noaccomp
noccp
lock
connect '/usr/sbin/chat -v -t6 -f /etc/ppp/peers/gsm_chat'

chat script output:
-------------------
SAY 'Starting Sierra Wireless GSM connect script...\n'
SAY '\n'

SAY 'Setting the abort string\n'
SAY '\n'
ABORT 'NO DIAL TONE' ABORT 'NO ANSWER' ABORT 'NO CARRIER' ABORT DELAYED

SAY 'Initializing modem\n'
'' AT
OK ATZ

SAY '\n'
SAY 'Setting APN\n'
OK 'AT+CGDCONT=1,"IP","airtelgprs.com"'

SAY '\n'
SAY 'Dialing...\n'
OK ATD*99#
CONNECT ''

pppd's logs:
------------
May 7 09:54:09 Bhaskar pppd[25242]: pppd 2.4.5 started by root, uid 0
May 7 09:54:10 Bhaskar chat[25253]: abort on (NO DIAL TONE)
May 7 09:54:10 Bhaskar chat[25253]: abort on (NO ANSWER)
May 7 09:54:10 Bhaskar chat[25253]: abort on (NO CARRIER)
May 7 09:54:10 Bhaskar chat[25253]: abort on (DELAYED)
May 7 09:54:10 Bhaskar chat[25253]: send (AT^M)
May 7 09:54:10 Bhaskar chat[25253]: expect (OK)
May 7 09:54:10 Bhaskar chat[25253]: AT^M^M
May 7 09:54:10 Bhaskar chat[25253]: OK
May 7 09:54:10 Bhaskar chat[25253]: -- got it
May 7 09:54:10 Bhaskar chat[25253]: send (ATZ^M)
May 7 09:54:10 Bhaskar chat[25253]: expect (OK)
May 7 09:54:10 Bhaskar chat[25253]: ^M
May 7 09:54:10 Bhaskar chat[25253]: ATZ^M^M
May 7 09:54:10 Bhaskar chat[25253]: OK
May 7 09:54:10 Bhaskar chat[25253]: -- got it
May 7 09:54:10 Bhaskar chat[25253]: send (AT+CGDCONT=1,"IP","airtelgprs.com"^M)
May 7 09:54:11 Bhaskar chat[25253]: expect (OK)
May 7 09:54:11 Bhaskar chat[25253]: ^M
May 7 09:54:11 Bhaskar chat[25253]: AT+CGDCONT=1,"IP","airtelgprs.com"^M^M
May 7 09:54:11 Bhaskar chat[25253]: OK
May 7 09:54:11 Bhaskar chat[25253]: -- got it
May 7 09:54:11 Bhaskar chat[25253]: send (ATD*99#^M)
May 7 09:54:11 Bhaskar chat[25253]: expect (CONNECT)
May 7 09:54:11 Bhaskar chat[25253]: ^M
May 7 09:54:11 Bhaskar chat[25253]: ATD*99#^M^M
May 7 09:54:11 Bhaskar chat[25253]: CONNECT
May 7 09:54:11 Bhaskar chat[25253]: -- got it
May 7 09:54:11 Bhaskar chat[25253]: send (^M)
May 7 09:54:11 Bhaskar pppd[25242]: Script /usr/sbin/chat -v -t6 -f /etc/ppp/peers/gsm_chat0 finished (pid 25253), status = 0x0
May 7 09:54:11 Bhaskar pppd[25242]: Serial connection established.
May 7 09:54:11 Bhaskar pppd[25242]: using channel 6
May 7 09:54:11 Bhaskar pppd[25242]: Using interface ppp3
May 7 09:54:11 Bhaskar pppd[25242]: Connect: ppp3 <--> /dev/ttyUSB0
May 7 09:54:12 Bhaskar pppd[25242]: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x9191ec04>]
May 7 09:54:12 Bhaskar pppd[25242]: rcvd [LCP ConfReq id=0x7 <asyncmap 0x0> <auth chap MD5> <magic 0x61b9069> <pcomp> <accomp>]
May 7 09:54:12 Bhaskar pppd[25242]: No auth is possible
May 7 09:54:12 Bhaskar pppd[25242]: sent [LCP ConfRej id=0x7 <auth chap MD5> <pcomp> <accomp>]
May 7 09:54:12 Bhaskar pppd[25242]: rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x9191ec04>]
May 7 09:54:12 Bhaskar pppd[25242]: rcvd [LCP ConfReq id=0x8 <asyncmap 0x0> <magic 0x61b9069>]
May 7 09:54:12 Bhaskar pppd[25242]: sent [LCP ConfAck id=0x8 <asyncmap 0x0> <magic 0x61b9069>]
May 7 09:54:12 Bhaskar pppd[25242]: sent [LCP EchoReq id=0x0 magic=0x9191ec04]
May 7 09:54:12 Bhaskar pppd[25242]: sent [IPCP ConfReq id=0x1 <addr 0.0.0.0>]
May 7 09:54:12 Bhaskar pppd[25242]: rcvd [LCP DiscReq id=0x9 magic=0x61b9069]
May 7 09:54:12 Bhaskar pppd[25242]: rcvd [LCP EchoRep id=0x0 magic=0x61b9069 91 91 ec 04]
May 7 09:54:13 Bhaskar pppd[25242]: sent [LCP EchoReq id=0x1 magic=0x9191ec04]
May 7 09:54:13 Bhaskar pppd[25242]: rcvd [IPCP ConfNak id=0x1 <ms-dns1 10.11.12.13> <ms-dns2 10.11.12.14> <ms-wins 10.11.12.13> <ms-wins 10.11.12.14>]
May 7 09:54:13 Bhaskar pppd[25242]: sent [IPCP ConfReq id=0x2 <addr 0.0.0.0> <ms-dns1 10.11.12.13> <ms-dns2 10.11.12.14> <ms-wins 10.11.12.13> <ms-wins 10.11.12.14>]
May 7 09:54:13 Bhaskar pppd[25242]: rcvd [LCP EchoRep id=0x1 magic=0x61b9069 91 91 ec 04]
May 7 09:54:14 Bhaskar pppd[25242]: sent [LCP EchoReq id=0x2 magic=0x9191ec04]
May 7 09:54:14 Bhaskar pppd[25242]: rcvd [IPCP ConfNak id=0x2 <ms-dns1 10.11.12.13> <ms-dns2 10.11.12.14> <ms-wins 10.11.12.13> <ms-wins 10.11.12.14>]
May 7 09:54:14 Bhaskar pppd[25242]: sent [IPCP ConfReq id=0x3 <addr 0.0.0.0> <ms-dns1 10.11.12.13> <ms-dns2 10.11.12.14> <ms-wins 10.11.12.13> <ms-wins 10.11.12.14>]
May 7 09:54:14 Bhaskar pppd[25242]: rcvd [LCP EchoRep id=0x2 magic=0x61b9069 91 91 ec 04]
May 7 09:54:14 Bhaskar pppd[25242]: Hangup (SIGHUP)
May 7 09:54:14 Bhaskar pppd[25242]: Modem hangup
May 7 09:54:14 Bhaskar pppd[25242]: Connection terminated.
May 7 09:54:15 Bhaskar pppd[25242]: Exit.