EPC EUTRAN LTE Mobile Networks Security Software Voice over IP

VoLTE/IMS Debugging on Samsung Handsets using Sysdump & Samsung IMS Logger

Unlocking the built in IMS Debugging tool in Samsung’s Sysdump Utility

Samsung handsets have a feature built in to allow debugging from the handset, called Sysdump.

Entering *#9900# from the Dialing Screen will bring up the Sysdump App, from here you can dump logs from the device, and run a variety of debugging procedures.

Samsung share information about this app publicly on their website,

Sysdump App in Samsung handsets used for debugging the device

But for private LTE operators, the two most interesting options are by far the TCPDUMP START option and IMS Logger, but both are grayed out.

Tapping on them asks for a one-time password and has a challenge key.

OTP Authentication required to unlock IMS Debugging and TCPDUMP on Samsung Sysdump tool

These options are not available in the commercial version of the OS and need to be unlocked with a one time key generated by a tool Samsung for unlocking engineering firmware on handsets.

Luckily this authentication happens client side, which means we can work out the password it’s expecting.

For those interested I’ve done a write up of how I reversed the password validation algorithm to take the key given in the OTP challenge and generate a valid response.

For those who just want to unlock these features you can click here to run the tool that generates the response.

Once you’ve entered the code and successfully unlocked the IMS Debugging tool there’s a few really cool features in the hamburger menu in the top right.

DM View

This shows the SIP / IMS Messaging and the current signal strength parameters (used to determine which RAN type to use (Ie falling back from VoLTE to UMTS / Circuit Switched when the LTE signal strength drops).

Screenshot of Samsung Sysdump tool in the IMS Debug - DM View section

Tapping on the SIP messages expands them and allows you to see the contents of the SIP messages.

Viewing SIP Messaging directly from the handset

Interesting the actual nitty-gritty parameters in the SIP headers are missing, replaced with X for anything “private” or identifiable.

Luckily all this info can be found in the Pcap.

The DM View is great for getting a quick look at what’s going on, on the mobile device itself, without needing a PC.


The real power comes in the logging functions,

There’s a lot of logging options, including screen recording, TCPdump (as in Packet Captures) and Syslog logging.

From the hamburger menu we can select the logging parameters we want to change.

Settings for Samsung IMS Logger

From the Filter Options menu we can set what info we’re going to log,

Filter options used in Dump output of Samsung IMS Logger application

If you’re leaning about VoLTE & IMS networks, or building your own, I’d suggest checking out my other posts on the topic.

5 replies on “VoLTE/IMS Debugging on Samsung Handsets using Sysdump & Samsung IMS Logger”

Nick I’ve run into a bit of a problem and I need a suggestion, please.
I’ve unlocked TCP Dump Start, but the IMS Logger has moved to a new location in the IMS settings under *#*#467#*#* (I had to use Google Dialer sadly).

My TCP Dumps are still unlocked but in IMS Logger the DumpMachine options have a password under Meminfo which doesn’t trigger a challenge key, so my IMS DM View logs have some information, but it’s not complete. The reason this is so urgent to me is that I got a bad version of QPST and I noticed it was forwarding some of my info to a GitHub address about my EFS, I’m not sure what info though.

Lately with the information I do get to see on IMS Logger, DM View has started to make me think my SIP ID has been jacked.
I get random cross country 11-digit numbers who apparently I’ve have had calls and messages with in the background but it only shows up in DM. It shows me content length in the messages but I can’t see what’s contained in them or what the file transfer was.

My calls always have a 3rd party added on too. I do not what to reflash my phone to because I will lose access to the USB settings to allow me into the EFS which I can’t pull of again, and I’m trying to figure something separate out.
I just need some suggestions on the IMS DumpMachine option page and how to retrieve it’s password so I can see the entire log.

Please email me if you get a chance, I could really use the advice. Big fan by the way.

Best Regards,

I’m trying to reach IMS Settings using a Samsung S21 and I cannot find it anymore. I used it a lot of times with Samsung S5, S6, S8. Do you have any idea how I can launch it ?
Do you know how “TCP dump start” works? I cannot generate any pcap file … (OTP step is ok)

Related to the tools, you can use Shannon DM to see all the messages exchanges by the Samsung phones with Exynos chipset and with the network.

If you have Qualcomm routed phones you can use Network Signal Guru a much better tool , take a lok at my blog: . You can join the NSG community on Telegram:


Hi Seth,
I don’t have access to the newer Samsung handsets, it’s possible that Samsung have caught onto this post and secured the system again and only have the option on Engineering Handsets.

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