No, there's no explanation that I can find.
6 seconds sound clip from the Champagne for Caesar movie soundboard.
You can hear this line at 01:07:53 in the DVD version of the movie.
Quote context
[...]
- Oh, it's awfully sweet of you to forgive me and please, don't cry anymore. Good bye.
- Five minutes in the shower? I called for four hours. Women.
- All right, let's forget the shower for the time being.
- One very good reason not to answer the phone is that you don't hear it.
- No, there's no explanation that I can find.
- Except of course that you don't hear the telephone when you're not at home.
(Parrot speaking) I'll buy that.
- Oh, come in darling, come in.
- I thought perhaps you'd like...
[...]