When phone is idle, on top taskbar, to the left of signal strength indicator, I have a H icon with arrows beneath it. What does this mean? Sometimes it switches to a 3G with the arrows. I know what a 3G network is, but a H network? Sorry I am not good with technical stuff. Lucky the phone is easy to use!
The H connection signifies a superior and faster connection, however if your phone is unable to make calls during this then there may be a device fault or issue.
If you confirm your location (post code) we can study the sites in your area and which of them are pushing out HSDPA (H), additionally, do you experience this problem in any other areas where you have an H signal?