Only it was not his sister.
Listening to the recorded conversations, police soon discovered Milford was actually speaking to the victim.
Milford told her it would be good if there was an affidavit saying nothing happened and that he needed evidence in his favour to say he did not commit the alleged crimes.
The court heard it became plain Milford was not speaking to his sister when he asked the person on the end of the phone to marry him.
She said yes.
Over the following weeks the phone calls continued.
Milford lamented he might be in prison as long as a year, that he would miss children's birthdays and his father might die before he got out.
He piled on the pressure.
On April 29, he dictated the contents of a new statement exculpating himself, which the victim later had sworn by a justice of the peace.
"It was a premeditated and sustained course of action to have the victim change her statement and affect her evidence with the sole purpose of undermining the course of justice that had started and was before the court," Judge Michael Crosbie said.
"It is as brazen and blatant and orchestrated as I've ever heard."
The judge said the court often saw victims of domestic violence attempt to change their statements and suspected influence from the offender, but rarely was the attempt to pervert the course of justice laid bare as it was in this case.
In Milford's initial offending, he argued with his partner and then threw a piece of wood at her.
She locked herself inside the house then jumped out of a bedroom window, breaking her foot in the process, before fleeing over a fence to a neighbour's.
The next day, when she returned to the home, Milford lay in wait and bundled her into a bedroom, pushing her on to the bed.
He told her: "you're going to die now" then choked her for several seconds.
Judge Crosbie said that Milford had a lengthy record of aggression and breaching protection orders.
"The combination of criminal history and the facts before me depict you as a violent and controlling man," he said.
Milford, who sported a bandage on his throat, told the court he had recently had six enlarged lymph nodes removed from his chest which were possibly cancerous.
The judge offered to delay the sentencing for medical confirmation of the man's condition but he wanted the matters dealt with.Milford was jailed for three and a-half years.