If "Sunday's on the phone with Monday" who is Tuesday on the phone with?

From, "She Came in Through the Bathroom Window':

She came in through the bathroom window
Protected by a silver spoon
But now she sucks her thumb and wanders
By the banks of her own lagoon

Didn't anybody tell her?
Didn't anybody see?
Sunday's on the phone to Monday,
Tuesday's on the phone to me

She said she'd always been a dancer
She worked at 15 clubs a day
And though she thought I knew the answer
Well I knew but I could not say.

And so I quit the police department
And got myself a steady job
And though she tried her best to help me
She could steal but she could not rob.