Writing Data in Firebase for IONIC

Please need little help trying to write data to firebase

"phoneNumbers" : {
    "07012345678": "user1",
    "06034345453": "user2",
    "09034564543": "user3",

How i do i achieve this in firebase, If i make use of set it simply creates the number and continue to update the same number and making use of push creates a unique for it which i dont want.any help please

just flow the link may be this link will help you to achieve your goal
Good Luck

Thanks you very much