Article in English: For an easy, temporary cell phone number, purchase a prepaid cell phone from a phone store, department store, or convenience store. Follow the instructions for activation, which usually involve calling the service provider from a landline or visiting their website.There is no requirement to give the service provider your name or personal information. If you require more airtime than what is provided with the phone, purchase an additional airtime card from the same provider and activate it the same way. To get a temporary new number for an unlocked cell phone, purchase a temporary use SIM card. Open up your phone and replace your current SIM card with the new one, and send a text to the number indicated on your card to activate it. Your new number will stay active until you run out of the minutes or data allotted with the card.  ZipSIM, for instance, offers temporary use SIM cards starting at $25 for a week’s worth of calls, texting, and data usage. Note that temporary SIM cards will only work with an unlocked phone. Register for a Skype number, which can be purchased in 23 different countries and used on your computer, tablet, or smartphone. Once it is bought and confirmed, you can distribute your number and receive audio calls on the device of your choice. This line can be used temporarily, or kept as a business line or second phone number. Prices for Skype numbers vary depending on region, but the cost is comprised of a flat fee for unlimited incoming calls. Google Voice is a popular option for a free phone number to manage your calls. This program (available for your computer, or Android or Apple device) gives you a new number that you can set to ring on all of your other lines (e.g. work phone, landline, cell phone). This function can also be used simply as an additional line, and can be kept temporarily or more permanently given your needs. Google Voice also has additional features like call blocking, voice mail, and call routing.

Summary in Vietnamese:
Mua điện thoại trả trước tạm thời. Mua thẻ SIM tạm thời. Đăng ký số Skype. Lấy số Google Voice.