[Q] How to debug a dropped call? - Android Q&A, Help & Troubleshooting

Hi,
I have been using a non-carrier-branded phone (HTC Desire -> stock ROM) without problems during more than one year. Voice and data OK. Carrier is Orange Spain.
Now, I've changed to a different carrier (Vodafone Spain) using and old SIM card I've been using during years in several old Nokia phones without problems (using only voice). As I don't have data yet in that old line, I've deactivated all data connections (3G and WIFI) in my HTC Desire.
With the Vodafone SIM card ALL calls drop after 10-20 seconds.
I ordered a duplicate of the SIM card and the problem still happens. Then I tried with my wife's Vodafone SIM card and the problem it's the same.
The problem happens at different places (home, office, gym...).
I've made a HARD reset without success.
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So, I'm running out of ideas. It seems that the problem root becomes from a combination of the phone and the carrier, worst possible scenario.
I'd like to debug the problem (mainly to know who is dropping the call, the carrier or the phone) but I don't know where I can change (if possible) the call trace level to DEBUG and where are the associated logs.
Maybe with the stock ROM is impossible. In that case, can anyone recommend me any ROM I can use to debug this problem?
Thanks
HTC Desire A8181
Android: 2.2
Baseband version: 32.49.00.32U_5.11.05.27
Kernel version: 2.6.32.15-gf5a401c [email protected] # 1
Build number: 2.29.405.5 CL293415 release-keys
Software number: 2.29.405.5

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Another idea:
Do you think that upgrading to v2.3 manually could solve the problem?

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Ok, I've found that using adb and logcat is possible to debug calls.
logcat -b radio
...
D/HTC_RIL ( 65): RX::> 3\r
D/HTC_RIL ( 65): (t=1320053119)%% 3\r
D/RILJ ( 197): [UNSL]< UNSOL_RESPONSE_CALL_STATE_CHANGED
D/HTC_RIL ( 65): RX::> @HTCDIS: 0000\r\n
D/RILJ ( 197): [0294]> GET_CURRENT_CALLS
D/HTC_RIL ( 65): (t=1320053119)%% @HTCDIS: 0000\r\n
D/HTC_RIL ( 65): ril_func_get_call_list():called
D/HTC_RIL ( 65): (t=1320053119)>> AT+CLCC\r
D/HTC_RIL ( 65): RX::> 0\r
D/HTC_RIL ( 65): (t=1320053119)<< 0\r
E/HTC_RIL ( 65): write_attr_file():failed to open attribute file: /sys/module/gpio_event/parameters/phone_call_status(errno=2)
E/HTC_RIL ( 65): write_attr_file():failed to open attribute file: /sys/module/gpio_event/parameters/phone_call_status(errno=2)
E/HTC_RIL ( 65): write_attr_file():failed to open attribute file: /sys/class/htc_accessory/phonein/flag(errno=2)
E/HTC_RIL ( 65): write_attr_file():failed to open attribute file: /sys/module/msm_flashlight/parameters/phone_status(errno=2)
D/RILJ ( 197): [UNSL]< UNSOL_RESPONSE_CALL_STATE_CHANGED
D/RILJ ( 197): [0295]> GET_CURRENT_CALLS
D/HTC_RIL ( 65): ril_func_get_call_list():called
D/RILJ ( 197): [0294]< GET_CURRENT_CALLS
D/HTC_RIL ( 65): (t=1320053119)>> AT+CLCC\r
D/HTC_RIL ( 65): RX::> 0\r
D/HTC_RIL ( 65): (t=1320053119)<< 0\r
E/HTC_RIL ( 65): write_attr_file():failed to open attribute file: /sys/module/gpio_event/parameters/phone_call_status(errno=2)
E/HTC_RIL ( 65): write_attr_file():failed to open attribute file: /sys/module/gpio_event/parameters/phone_call_status(errno=2)
D/RILJ ( 197): [0295]< GET_CURRENT_CALLS
D/RILJ ( 197): [0296]> LAST_CALL_FAIL_CAUSE
D/HTC_RIL ( 65): ril_func_get_last_call_fail_cause():called
D/HTC_RIL ( 65): (t=1320053119)>> AT\r
D/HTC_RIL ( 65): RX::> 0\r
D/HTC_RIL ( 65): (t=1320053119)<< 0\r
D/RILJ ( 197): [0296]< LAST_CALL_FAIL_CAUSE {65535}
D/GSM ( 197): [GSMConn] onDisconnect: cause=ERROR_UNSPECIFIED
D/GSM ( 197): GSMDataConnTrack handleMessage { what=15 when=2545321 [email protected] }
D/GSM ( 197): [GsmDataConnectionTracker](0)***trySetupData due to 2GVoiceCallEnded
D/GSM ( 197): [DSAC DEB] trySetupData with mIsPsRestricted=false
D/GSM ( 197): [GsmDataConnectionTracker](0)isDataAllowed()true, mRequestedApnType = default
D/GSM ( 197): [GsmDataConnectionTracker](0)isDataAllowed()true, mRequestedApnType = default
D/GSM ( 197): [GsmDataConnectionTracker](0)trySetupData: Not ready for data: dataState=IDLE gprsState=0 sim=true UMTS=true phoneState=IDLE isDataAll
false dataOnRoamingEnable=false ps restricted=false desiredPowerState=true setting=false MasterDataEnabled=true isPowerSavingModeActivated=false
D/GSM ( 197): GSMDataConnTrack handleMessage { what=15 when=2545322 [email protected] }
D/GSM ( 197): [GsmDataConnectionTracker](1)***trySetupData due to 2GVoiceCallEnded
D/GSM ( 197): [DSAC DEB] trySetupData with mIsPsRestricted=false
...
It seems that carrier is disconnecting the call, but why?
I updated radio to 5.14.05.17 and 5.17.05.23 without success. I've also tried to use CM7 7.0.3 and CM 7.1... but it's no working...
Any idea?