Creative writing snippet - Eldritch horror on the line?

I've handed in my first creative writing assignment - 200 odd words of free writing with only the start dictated by the tutor.

It's only gone through one rewrite so it's pretty raw, and proof that when all else fails I can always write bad science fiction about telephone trauma. :-)

All constructive feedback welcome.

He had hardly waited five minutes when the phone rang. Once, twice, its baleful analogue bleep passing out through the smashed glass of the booth, breaking the quiet of the small-hours side-road.

The man, swathed in hat and jacket and scarf, balances a notebook atop the telephone. Pen in right hand, he grabs for the receiver with over-haste, like a drunk reaches for the shot-glass.

He lifts it to his ear and speaks a word you do not understand. Then another, then a whole chain of nonsense syllables from which names periodically emerge: Washington; McAfferty; Kabul. Devoid of context, they float in the air, erased signs.

At length, the man finishes his … report? Recitiation? Ritual? In the phone box, there is a moment's silence as the unseen auditor digests it. Then, a hiss of static and an ululation like a thousand theremin echo from the speaker around the graffiti and steel of the booth.

The voice speaks.

Not bothering to modulate itself for private conversation … or indeed human hearing … each syllable drops in tones of crashing, contemptful lead onto the listener and out into the nighttime street.

The man in the booth reels in dismay at the exchange, buckles, scrabbles at the walls with his free hand like a cat down curtains. Yet he cannot let go of the receiver.