Because they are not a mobile cell operator and their technology is DATA ONLY. The guys are right, we've committed to GSM and 4G would be LTE for us not WIMAX. That technology has been relegated as a internet service. The Government has only issued a limited number of license for operating WIMAX so how do you expect a wide scale implementation?

Also WIMAX 'doesn't connect' to our cell phone infrastructure like WCDMA, HSDPA. These are part of the GSM infrastructure. So LTE is the answer.

VOIP and mobile phone are two entirely different products. You want a phone to be reliable and act like one. I don't think telcos will offer VOIP as a staple diet though.