I have two independent cases of SPA525G1 and G2 being used as teleworker phones spontaneously rebooting during calls. They are running the latest software (7.4.8). It doesn't happen at any other time, only during phone calls. The SPA525G1 is my office phone which I use from our remote office and the 525G2 belongs to a customer using it remotely to their UC540. Both UC540's are running 15.0(1)XA3a. They typically will reboot at some point during every phone call. I haven't opened a case on this yet.