No service or Emergency calls only
Both error messages are ambiguous. Both of these mean that the phone wasn't able to successfully connect to a tower and log in to a carrier, but don't give a reason.
No service indicates that there is no valid signal available. For example, if your phone or a carrier does not support 4G emergency calling on a carrier, 4G is marked invalid. When there is none left or the phone is searching, No service is displayed.
Emergency calls only indicates that the phone is not logged in, but it is still currently measuring signal and loading settings from a tower, such as settings that explain how to connect. The signal being measured is not necessarily from your carrier. When an emergency call is made, the phone connects to the part of the tower it is measuring and attempts to log in to the carrier, with the type set to Emergency. Therefore, the carrier can distinguish between phones logging in normally and phones logging in during emergencies.
Not registered on network indicates either of these.
How to troubleshoot
ServiceMode is a useful diagnostic tool. It can be opened by dialing *#0011# in Samsung's Phone app. If it does not open correctly, refer to Menu does not work.
Once the menu is opened, it is either ready, or requires selecting the SIM slot that's affected by the issue. If the menu displays LDU, the device is a Live Demo Unit and does not support cellular.
Determine the variant of the software that you have. Common ones are shown here: Variants.
For E. (device equipped with Exynos)
Step 1. Cause
After entering *#0011#, check LTE PS/CS Cause and GMM/MM Cause. If at least one of these are not 0/0, then the carrier sent a message equivalent to logging in failed due to ... or you were logged off due to...
Try toggling Airplane Mode to clear the Cause. What you can do depends on what the Cause is. If unsure, contact your carrier, your carrier sent the Cause.
Try toggling Airplane Mode to clear the Cause. What you can do depends on what the Cause is. If unsure, contact your carrier, your carrier sent the Cause.
If LTE PS/CS Cause and GMM/MM Cause are not displayed, note that LTE PS/CS REJECT and GMM/MM REJECT are equivalent, but if these aren't displayed, you have an old version of the software, try these alternatives.
This alternative may be useful because Causes are not available in old versions of the software, or to obtain a PDNConnectReject Cause that caused Cause 19. The alternative can be used by: *#9900# -> Run CP based log -> Copy to sdcard(include CP Ramdump). These files may be created:
- /sdcard/log/err/LitmusLog*.txt - Contains the 5 most recent Causes. Do not freely share the output, as it may reveal the tower you were connected to.
- /sdcard/log/err/ss_log/*/PROTOCOL.txt - Newer versions display the cause, i.e. [LTE NAS] AttachReject [19], older versions don't, i.e. [LTE NAS] AttachReject.
- /sdcard/log/err/ss_log/*/CP_MEMBERS.txt - Search for ATT FAIL or PDP FAIL, the EMMC, ESMC, or ENDR is the Cause. Do not freely share the output, as it may reveal the tower you were connected to.
Use
logcat, such as with the PC program ADB, specify adb logcat -s BigDataInfoController or adb logcat -s SemBigDataInfoControllerDo not freely share the output, as it may reveal the tower you were connected to.
To summarize, if any Cause or REJECT is not 0/0, then it's the cause of the Emergency calls only or No service issue. If these are 0/0, proceed to the next step.
Step 2. IMEI Status
The IMEI Status shall be OK, if it is OK, proceed to the next step. If it is NG, then it's the cause of the Emergency calls only or No service issue, take the phone to its authorized service center.
Step 3. MIPI TEST
MIPI FAIL being displayed is abnormal, if MIPI FAIL is displayed, then it's the cause of the Emergency calls only or No service issue. If MIPI FAIL is not displayed, proceed to the next step.
Step 4. RRC
After using Airplane Mode, RRC shall not cycle between IDLE and WAIT_RRC_CONFIRM. If it does, then the phone can't connect to the tower. The following may prevent connection:
- The uplink signal strength (from the phone to the tower) might be too weak. To attempt to make it work anyway: 1. Ensure the antenna responsible for uplink isn't held in a way that it's muffled, note that this normally isn't required, but if the signal is too weak, not much can be done. 2. Disconnect any cable (USB, headphone, etc), and use the phone in a way that doesn't trigger the grip sensor. 3. Move the phone around until where the tower can detect it is discovered.
- The tower might not be waiting long enough. Ask your carrier to consider changing its preamble format, so it waits longer and can be used from farther away.
For S. (device equipped with Snapdragon)
Step 1. Cause
There is no Cause value available after entering *#0011#. Causes are equivalent to logging in failed due to ... or you were logged off due to ...
Though the exact Cause is not displayed, RoNotAl/LUNotAl/NoIMSI may indicate that a Cause was received.
Though the exact Cause is not displayed, RoNotAl/LUNotAl/NoIMSI may indicate that a Cause was received.
*#9900# -> Run CP based log -> Copy to sdcard(include CP Ramdump). These files may be created:
- /sdcard/log/err/ss_log/*/BIGDATA.txt - Search for ATTF, then the EMMC or ESMC. Do not freely share the output, as it may reveal the tower you were connected to.
- /sdcard/log/err/ss_log/*/SM.txt - Search for cause.
Use
logcat, such as with the PC program ADB, specify adb logcat -s BigDataInfoController or adb logcat -s SemBigDataInfoControllerStep 2. FINAL IMEI Certi
If FINAL IMEI Certi: PASS, proceed to the next step. If FAIL is displayed, then it's the cause of the Emergency calls only or No service issue, take the phone to its authorized service center.
This alternative may be useful if there is a false negative: *#9900# -> Run CP based log -> Copy to sdcard(include CP Ramdump). These files may be created:
- /sdcard/log/err/LITMUS_UIM_Info*.txt - Certi: PASS (normal); Certi: FAIL (abnormal)
Step 3. MIPI TEST
MIPI DEVICE FAIL being displayed is abnormal, if MIPI DEVICE FAIL is displayed, then it's the cause of the Emergency calls only or No service issue. In newer versions of the software, this feature is now simply outside the menu, use this alternative.
Step 4. RRC
After using Airplane Mode, RRC shall not cycle, entering and exiting WFRC without CONN. If it does, then the phone can't connect to the tower. The following may prevent connection:
- The uplink signal strength (from the phone to the tower) might be too weak. To attempt to make it work anyway: 1. Ensure the antenna responsible for uplink isn't held in a way that it's muffled, note that this normally isn't required, but if the signal is too weak, not much can be done. 2. Disconnect any cable (USB, headphone, etc), and use the phone in a way that doesn't trigger the grip sensor. 3. Move the phone around until where the tower can detect it is discovered. 4. If TM is displayed, ensure TM is 0.
- The tower might not be waiting long enough. Ask your carrier to consider changing its preamble format, so it waits longer and can be used from farther away.
For M. (device equipped with MTK)
Step 1. Cause
There is no Cause value available after entering *#0011#. Causes are equivalent to logging in failed due to ... or you were logged off due to ...
Use
logcat, such as with the PC program ADB, specify adb logcat -s BigDataInfoController or adb logcat -s SemBigDataInfoControllerStep 2. IMEI Certi
If IMEI Certi: PASS, proceed to the next step. However, if FAIL is displayed instead, then it's the cause of the Emergency calls only or No service issue, take the phone to its authorized service center.
Step 3. MIPI TEST
MIPI TEST FAIL being displayed is abnormal, if MIPI TEST FAIL is displayed, then it's the cause of the Emergency calls only or No service issue.
Step 4. RRC
After using Airplane Mode, RRC shall not cycle without entering CONN. If it does, then the phone can't connect to the tower. The following may prevent connection:
- The uplink signal strength (from the phone to the tower) might be too weak. To attempt to make it work anyway: 1. Ensure the antenna responsible for uplink isn't held in a way that it's muffled, note that this normally isn't required, but if the signal is too weak, not much can be done. 2. Disconnect any cable (USB, headphone, etc), and use the phone in a way that doesn't trigger the grip sensor. 3. Move the phone around until where the tower can detect it is discovered.
- The tower might not be waiting long enough. Ask your carrier to consider changing its preamble format, so it waits longer and can be used from farther away.
Step 5. Other reasons
Here's what else might cause this issue:
No valid signal
No valid signal, hence no service. If there is a tower nearby, it might be a tower for some other carrier, it might not be operational, or it might not be a cell tower. There might be no signal at all, or there might be signal available but the phone is not allowed to use it. Examples: 1. the phone is set to 3G only but only 4G is available; 2. the phone is set to Band 1 only but only Band 3 is available; or 3. there is only 4G available but the SIM currently inserted is not a USIM or newer.
Cell Barring
Cell Barring is a kind of setting that may be loaded from a part of a tower. There are many kinds of cell barring:
- Unconditional - once a phone loads this from a part of the tower, the phone acts as if the part of the tower doesn't exist.
- Reserved for operator use - note that aside from what its name indicates, phones process it differently compared to 'unconditional' barring.
- Access class barring - Each SIM has an access class, SIMs of certain access classes can be barred, others are allowed entry.
- Random - Phone generates a random number, if lucky, not barred, else temporarily barred. Eases congestion.
- SSAC barring - Certain services may be barred, other services are not barred.