About 1000 people will participate in the trial from July until early next year, using their phones to tap on and off, and top up as well as check their Myki balance, Public Transport Minister Jacinta Allan says.

The trial will cost between $2 and $3 million and only apply to android users but the government says the technology could eventually be used in other phones as well.

"This will mean that the phones can store the card and people will be able to use the existing readers, the existing gates to participate in the trial," Ms Allan told reporters on Monday.

But she said the physical Myki card system, a $700 million contract running until 2023, would not be phased out.

"Those cards will always exist because not everybody will want to use the technology in this way," Ms Allan said.

A decision will be made about the future of the virtual Myki technology next year.

"It's important to get this right. This is new technology, it's not been trialled anywhere else in the world on a multi-modal scale," the minister said.

Australian Associated Press