Re: QC35 and QC30 for communications
Nowhere on the product page does it discourage use for calls in anything but an anechoic chamber. In fact, it says:
Wireless sound without compromises
Leave the wires behind—without sacrificing performance. The volume-optimized EQ delivers consistent, balanced sound at any volume. If you’re on a busy street and need to turn it up, the sound stays true to your music. And they’re re-engineered with Bluetoothand NFC pairing, so connecting to your devices wirelessly is quick and easy. An inline remote lets you take/end calls, skip/pause tracks and control volume without reaching for your device. So you can focus on the music.
And then futher down in the FAQ's:
What happens to the noise cancelling level during a call?