Since upgrade from 12.04 to 12.10 I can't connect to internet using mobile broadband modem Huawei e173. It worked earlier without problems and now it seems to be properly recognized (at least its connections appear in network manager applet), and after selecting connection manually it starts connection procedure. After about 20 seconds it returns to state disconnected.

After browsing internet I've found that running network manager with:

NM_PPP_DEBUG=1 /usr/sbin/NetworkManager --no-daemon

After inserting modem I get:

NetworkManager[507]: <warn> (ttyUSB2): failed to look up interface index
NetworkManager[507]: <info> (ttyUSB2): new GSM/UMTS device (driver: 'option1' ifindex: 0)
NetworkManager[507]: <info> (ttyUSB2): exported as /org/freedesktop/NetworkManager/Devices/2
NetworkManager[507]: <info> (ttyUSB2): now managed
NetworkManager[507]: <info> (ttyUSB2): device state change: unmanaged -> unavailable (reason 'managed') [10 20 2]
NetworkManager[507]: <info> (ttyUSB2): deactivating device (reason 'managed') [2]
NetworkManager[507]: <info> (ttyUSB2): device state change: unavailable -> disconnected (reason 'none') [20 30 0]

where 'failed to look up interface index' seems to be suspicious.

After starting connecting:

NetworkManager[507]: <info> Activation (ttyUSB2) starting connection 'Plus - Dostep standardowy'
NetworkManager[507]: <info> (ttyUSB2): device state change: disconnected -> prepare (reason 'none') [30 40 0]
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 1 of 5 (Device Prepare) scheduled...
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 1 of 5 (Device Prepare) started...
NetworkManager[507]: <info> (ttyUSB2): device state change: prepare -> need-auth (reason 'none') [40 60 0]
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 1 of 5 (Device Prepare) complete.
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 1 of 5 (Device Prepare) scheduled...
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 1 of 5 (Device Prepare) started...
NetworkManager[507]: <info> (ttyUSB2): device state change: need-auth -> prepare (reason 'none') [60 40 0]
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 1 of 5 (Device Prepare) complete.
NetworkManager[507]: <info> WWAN now enabled by management service
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 2 of 5 (Device Configure) scheduled...
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 2 of 5 (Device Configure) starting...
NetworkManager[507]: <info> (ttyUSB2): device state change: prepare -> config (reason 'none') [40 50 0]
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 2 of 5 (Device Configure) successful.
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 3 of 5 (IP Configure Start) scheduled.
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 2 of 5 (Device Configure) complete.
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 3 of 5 (IP Configure Start) started...
NetworkManager[507]: <info> (ttyUSB2): device state change: config -> ip-config (reason 'none') [50 70 0]
NetworkManager[507]: <info> starting PPP connection
NetworkManager[507]: <info> pppd started with pid 663
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 4 of 5 (IPv6 Configure Timeout) scheduled...
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 3 of 5 (IP Configure Start) complete.
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 4 of 5 (IPv6 Configure Timeout) started...
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 4 of 5 (IPv6 Configure Timeout) complete.
Plugin /usr/lib/pppd/2.4.5/nm-pppd-plugin.so loaded.
** Message: nm-ppp-plugin: (plugin_init): initializing
** Message: nm-ppp-plugin: (nm_phasechange): status 3 / phase 'serial connection'
Removed stale lock on ttyUSB2 (pid 32146)
using channel 23
NetworkManager[507]:    SCPlugin-Ifupdown: devices added (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
NetworkManager[507]:    SCPlugin-Ifupdown: device added (path: /sys/devices/virtual/net/ppp0, iface: ppp0): no ifupdown configuration found.
NetworkManager[507]: <warn> /sys/devices/virtual/net/ppp0: couldn't determine device driver; ignoring...
Using interface ppp0
Connect: ppp0 <--> /dev/ttyUSB2
** Message: nm-ppp-plugin: (nm_phasechange): status 5 / phase 'establish'
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x64b4024a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x64b4024a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x64b4024a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x64b4024a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x64b4024a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x64b4024a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x64b4024a> <pcomp> <accomp>]
NetworkManager[507]: <warn> pppd timed out or didn't initialize our dbus module
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 4 of 5 (IPv4 Configure Timeout) scheduled...
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 4 of 5 (IPv4 Configure Timeout) started...
NetworkManager[507]: <info> (ttyUSB2): device state change: ip-config -> failed (reason 'ip-config-unavailable') [70 120 5]
NetworkManager[507]: <warn> Activation (ttyUSB2) failed for connection 'Plus - Dostep standardowy'
NetworkManager[507]: <info> Activation (ttyUSB2) Stage 4 of 5 (IPv4 Configure Timeout) complete.
NetworkManager[507]: <info> (ttyUSB2): device state change: failed -> disconnected (reason 'none') [120 30 0]
NetworkManager[507]: <info> (ttyUSB2): deactivating device (reason 'none') [0]
Terminating on signal 15
** Message: nm-ppp-plugin: (nm_phasechange): status 10 / phase 'terminate'
sent [LCP TermReq id=0x2 "User request"]
NetworkManager[507]:    SCPlugin-Ifupdown: devices removed (path: /sys/devices/virtual/net/ppp0, iface: ppp0)

where repeated:

sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x64b4024a> <pcomp> <accomp>]

last for about 20 seconds.

I've tried to downgrade network manager but failed due to many dependencies.

Can anyone point me to solution or tell what should I do to further investigate the problem?