Hún skellti á pabba minn þegar hann sagðist koma klukkan sjö.
She hung up on my dad when he said he'd arrive at seven o'clock.
Usage notes
The verb skella á has a harsher and more of a negative connotation (akin to slamming the phone down) than the verb leggja á which has a softer meaning (akin to laying the phone down).