VoLTE Lab is a complete test suite for Voice-over-LTE, that includes the LTE LabKit, the Yate MiniCore and two iPhone 6s. It is fully configured and intended for use as a VoLTE test bed and learning environment.

With VoLTE Lab you can have a deep view into the internals of VoLTE technology, with Wireshark.
You can run Wireshark on the LTE Phy radio interface.
You can run Wireshark on S1-MME and S1-U interfaces and also on the S6a interface.