I would like to let you know that sharing contact information before a contract has started is against Upwork's Terms of Service and that all communications prior to the contract starting must take place on Upwork. A real client will never ask you to give them money to start working, cash a check for them, work for free, or provide your personal information.
Could you please click on my name above this post and send me a private message with more information about the job you're referring to? The link to the job post will be extremely helpful. We encourage you to let us know if a TOS violation has happened by using the Flag as Inappropriate option throughout the platform. You can learn more about user reporting here. You may also want to check this help article and this thread for more information on how to stay safe on Upwork.