[url=https://www.youtube.com/watch?v=BZrN1lsAVMM][i]Here we are, don't turn away now,
we are the warriors that built this town. [/i][/url]

The off-pitch metalic sound of a phone that's been trough more than any phone ever should valiantly resounded trough Magnus's Lair.
It was his phone after all.

[i]Here we are, don't turn away now,
we are the warriors that built this town from dust.[/i]

He'd obviously know by the specific ringtone It'd be Hale calling.
He probably already knew everything Hale would tell him, he'd probably tell him about how the mission to Canada was a success. 
How he had the beginnings of a fresh wolf army wrapped up and ready to go.
And it wouldn't surprise anyone, especially not Magnus, if Hale had found something stupid and explosive.

[i]This time will come when you will have to rise,
Above the best and prove yourself your spirit 
never dies.[/i]

Chances Hale had anything to say Magnus wouldn't expect were small indeed.
No, the main argument towards picking up the phone was to smother that damn ringtone.