When did Carolyn call Bob?

(Carolyn=W, Bob=M)
W: Bob, you weren’t at home last Saturday, were you? I tried to call you.
M: Oh, that’s right, Carolyn. I suppose you phoned me in the morning, didn’t you?
W: Yes, it was late in the morning when I phoned.
M: Oh, I was out shopping. Why did you phone me?
W: I wanted to ask if you’d like to come to dinner on Sunday.
M: Oh, what a pity! I wish I had come but—actually, I went on a river trip practically the whole day Sunday.
W: How was the trip?
M: Very worthwhile. By the way, how did the dinner party go?
W: Well, we had a wonderful time... er... I thought you might have enjoyed it too if you had come. Tom Welsh and his wife were with us. You’ve met them before, haven’t you?
M: Tom Welsh, yes, I rather liked him.
W: And we had a lovely dinner with green cabbage, cucumber soup and fresh salad.
M: Very nice.
W: And they asked about you.
M: And how’re they getting on?
W: Oh, very well. They enjoyed the party very much.
M: Ah, good.