If I use my mobile internet heavily (surfing, facbook videos, download, internet mesaging) I get a 20% failed switching rate.
I understand that when you use LTE and an incoming or outgoing call occurs, the mobile network automatically switches to 3G or 2G signal to enable voice. However I also sometimes observed that the network failed to switch to 3G or 2G signal. At first I suspect that it was my phone, but after changing mobile phone I still get the same problem.
You may ask if how did I know that the switching failed. I actually set my globe to divert to my smart number if it is out of reach. So then my smart mobile phone is ringing with a "tagged" note that it was a diverted call.