I would do the following in this order:
1) answer the phone
2) (while talking on the cordless phone) pour the milk into the tea/coffee (whichever I feel like that day)
3) drink the tea/coffee without slurping while still on the phone.
There, easy as that :-P
I used to be a big tea drinker, then I was a big coffee drinker, now I'm turning back to tea again :-)