Hello.
It's often handy to have a high-level look at message exchange between ms and gsm network captured via gsmtap.
There are some tools to do that for ip captures but they completely ignore uplink-downlink semantics so are next to useless in this case.
Attached is little helper which can be used to make proper descriptions for mscgen to produce nice message sequence charts. Usage instructions are inside the script. In short: .pcap in - .png out
It requires mscgen and recent (>=1.9) tshark so you have to use git to get and build tshark binary yourself until wireshark 1.10 is released:
git clone http://code.wireshark.org/git/wireshark
Apologies if you received this message multiple times but I personally find this little helper to be very useful so I'd like to reach as wide audience as possible.