There may be a setting you have to enable Modem mode in order for a Wlan client to use the phone's internet account. Since you didn't bother to give any detail of your phone make/model we cannot even read your manual for you.
The information on Computing.Net is the opinions of its users. Such
opinions may not be accurate and they are to be used at your own risk.
Computing.Net cannot verify the validity of the statements made on this
site. Computing.Net and Purch hereby disclaim all responsibility
and liability for the content of Computing.Net and its accuracy.