Hey folks,
I can confirm that the Sony Xperia X does support Voice over LTE, tested with T-Mobile Germany.
BUT:
a) Only supported for branded devices
b) Must call T-Mobile hotline and explicitly activate Voice over LTE option
c) Works only if BOTH parties have branded T-Mobile smartphones and with sufficient LTE coverage
Sound quality is amazing (tested between Xperia X and Z5), really CD quality!
I suppose that for Vodafone DE it would be the same (and same precautions)
