New M2A HSPA+ connectivity problem (critical)

Nov 26, 2013
Device: M2A; Android 4.1, MIUI 3.11.8
Placing a phone call the phone does not give me a tone after the dial or it disconnects me immediately and this is happening quite often.
I found out that this is probably related with some misbehaviour of the phone over HSPA+ networks and probably this problem won't be present if I force my phone to 2G networks only but what's the point to have a smartphone and use it only on 2G? This problem is very annoying and should be rated at least as major or critical.
There is a thread in Spanish forums about the matter with screenshots
and it was reported in English site at 7 Jul
It causes this phone is not recommended to buy for users and sellers
Some mobile stores don't want to sell a MI2A .... The reason is ... This mobile has problems ...
This is what He says :D