Is Apple's CDMA+LTE chip the reason it can't do Voice+Data on Verizon/Sprint?

Looks like it is due to the one-chip design: <a href="http://arstechnica.com/apple/2012/09/still-no-simultaneous-voice-and-data-on-the-verizon-or-sprint-iphone-5/" rel="nofollow">http://arstechnica.com/apple/2012/09/still-no-simultaneous-v...</a>