On the return trip out of TEB the route was straight into New York Oceanic FIR. We couldn't get the clearance via datalink. We received total two new re-clearances on ground with Teterboro Clearance. We logged on with FANS and CPDLC with NEW YORK CTA KZWY already on Ground before Take off. The transition was straight and easy into New York Oceanic airspace. We flew the OTS. The route was quite south via New York - Gander - Shanwick. CPDLC worked fine. Also the transition to next FIR was automatically. The mandatory Selcal Check on HF was straight forward. We had to cross a frontal system with high tops. Having CPDLC made deviations also easy. Asked for higher Altitude and 30NM left of Track to deviate via CPDLC. Got straight the clearance
. Imagine asking deviations via HF would have been a nightmare.