[Android Q&A, Help & Troubleshooting] biswaranjan:
I can understand your frustration and pain.. I have gone through the same for past few months. I had verified with 64k, 128k and 256k sims. None of them fixed the issue. It reboots with any kind of sim. so buying a 128k sim will not help. But, only sim I have not verified is 'LTE sim with 3g/2g support'. It might fix the issue.

However as a workaround, I have modified some android props to suit Indian network conditions and the phone is much stable with a 64k sim now ! Still there were two reboots in three days(found the cause, will fix it) and it never rebooted during call ! Earlier it used to reboot 5-6 times a day. It used to reboot during/after calls, when kept idle, when I am cooking, etc...

Fix is to disable LTE on this phone and set some 3g/2g parameters. Additionally you can set some default locale and gps config too.

Please do the following tweaks and let us know the result.

Steps: (search the forum for appropriate links)

1. root your phone and mount /system as read/write. (must)

2. Now disable LTE and configure 3g/2g parameters: Add the following lines to "/system/build.prop" file. (can directly copy paste the following at end of the file)

# system props for telephony modules

# Disable LTE/4G

ro.config.lte=false

# Set default network to be 3g/2g auto (wcdma preferred)

ro.telephony.default_network=0

# set hsdpa/hsupa categories

ro.ril.hep=0

# hsxpa=2 signifies hsdpa and hsupa. you can leave it as 2.

ro.ril.hsxpa=2

# gprsclass=12 is maximum value it can have. all modern networks should support this, else as a conservative setting try 10.

ro.ril.gprsclass=12

# hsdpa=8 and hsupa=6 signifies 7.2mbps dowenload/5.76mbps upload. If your network supports it, leave it as it is. else try 6/4 for these values

ro.ril.hsdpa.category=8

ro.ril.hsupa.category=6

# some signal strength, power tweaks

ro.ril.att.feature=1

ro.ril.disable.power.collapse=1

ro.ril.fast.dormancy.rule=1

ro.config.hw_fast_dormancy=1

# fixes connectivity issues, my phone used to loose network very often.

ro.ril.enable.dtm=0

ro.ril.enable.a53=0

# believed to be signal strength tweaks

ro.ril.enable.ncell.ind=1

ro.telephony.ril.v3=signalstrength,singlepdp,skipbrokendatacal

# better voice quality

ro.ril.enable.amr.wideband=1

3. Now set gps settings in build.prop. Add the following lines to "/system/build.prop" file. (can directly copy paste to the file)

# AGPS mode set

ro.ril.def.agps.mode=2

ro.ril.def.agps.feature=1

4. Now change locale settings. (So that when you do a factory reset, it does not show you japanese text) Find out following props and change it. (in "/system/build.prop" )

ro.product.locale.language=en

ro.product.locale.region=US

5. Now lets fix gps settings: (replace contents of "/system/etc/gps.conf" with the following). you should set NTP_SERVERS for your region. rest of the things should be fine for your region.

NTP_SERVER=asia.pool.ntp.org

NTP_SERVER=0.asia.pool.ntp.org

NTP_SERVER=1.asia.pool.ntp.org

NTP_SERVER=2.asia.pool.ntp.org

NTP_SERVER=3.asia.pool.ntp.org

NTP_SERVER=0.vn.pool.ntp.org

NTP_SERVER=1.asia.pool.ntp.org

NTP_SERVER=0.asia.pool.ntp.org

XTRA_SERVER_1=http://xtra1.gpsonextra.net/xtra.bin

XTRA_SERVER_2=http://xtra2.gpsonextra.net/xtra.bin

XTRA_SERVER_3=http://xtra3.gpsonextra.net/xtra.bin

# DEBUG LEVELS: 0 - none, 1 - Error, 2 - Warning, 3 - Info

# 4 - Debug, 5 - Verbose

DEBUG_LEVEL =0

# Intermediate position report, 1=enable, 0=disable

INTERMEDIATE_POS=0

# Accuracy threshold for intermediate positions

# less accurate positions are ignored, 0 for passing all positions

ACCURACY_THRES=0

# Report supl ref location as position, 1=enable, 0=disable

REPORT_POSITION_USE_SUPL_REFLOC=1

# Wiper (wifi positioning), 1=enable, 0=disable

ENABLE_WIPER=1

################################

##### AGPS server settings #####

################################

# FOR SUPL SUPPORT, set the following

SUPL_HOST=supl.google.com

SUPL_PORT=7276

SUPL_NO_SECURE_PORT=3425

SUPL_SECURE_PORT=7275

SUPL_TLS_HOST=FQDN

SUPL_TLS_CERT=/etc/SuplRootCert

# FOR C2K PDE SUPPORT, set the following

C2K_HOST=c2k.pde.com

C2K_PORT=1234

CURRENT_CARRIER=common

DEFAULT_AGPS_ENABLE=TRUE

DEFAULT_SSL_ENABLE=FALSE

# TRUE for "User Plane", FALSE for "Control Plane"

DEFAULT_USER_PLANE=TRUE

6. Change some parameters in "/system/etc/gps/config/pathconfigfile.txt". Replace the file with following content.

#

# Config file

GPSC_CONFIG_FILE /system/etc/gps/config/GPSCConfigFile.cfg

# Patch file

PATCH_FILE /system/etc/gps/patch/patch-X.0.ce

# Aiding file storage

AIDING_PATH	/cache/gps/aiding/

#Logger Control

#0->dont log:

#1-> UDP

#2-> NVM

#3-> ANDROID

#4-> STDIO

#5-> CUSTOM FUNC

LOGGER_CONTROL 0

#logger IP & PORT when LOGGER_CONTROL = 1, else ignored

DEBUG_UDP 192.168.16.1 5555

#Logger NVM setting, when LOGGER_CONTROL = 2, else ignored

LOGGER_NVM_FILE /cache/gps/logs/

#Logger - maximum lines in log per file in NVM

MAX_LOG_LINES 100000

#Logger - maximum log files in NVM

MAX_NVM_FILES 10

#To/From Sensor Control

#0->Dont write:

#1->Write to UDP(Not supported):

#2->Write to NVM:

SENSOR_CONTROL 0

#Sensor log NVM setting

SENSOR_NVM_PATH /cache/gps/logs/

#Session log Control

#0->Dont write

#1->Write to NVM

SESSION_LOG_CONTROL 0

#Session log NVM setting

SESSION_LOG_NVM_PATH /cache/gps/logs/

6. Now, DO A FACTORY RESET. AND PLS DO NOT DISABLE ANY DOCOMO APPS. Use the phone for couple of days and if it's stable, start disabling docomo apps.

Please do let me know if it helped.

Note: still you might see a reboot, as I had seen two reboots in last three days. Found the cause, fixed it and device is under test again :) Let's hope no more reboots on this device.

PS: I hate this device so much, if it reboots again I will throw it out of the window.

How can some one release a device without proper verification ? a docomo user might face same issues while in international roaming !