Techniques are disclosed relating to facilitating transactions via mobile devices. In one embodiment, an account that is linked to a mobile telephone number of a mobile device is established at a computer system. In such an embodiment, the account permits a user to make and receive payments, and is not accessible without using the mobile device. In some embodiments, the account is established without setting up a username and password. In one embodiment, a request is sent from a payment application of the mobile device to the computer system. In some embodiments, the payment application is made active on the mobile device in response to a user input within a different application running on the mobile device. After the payment application is active, a purchase is confirmed within the payment application such that the request is sent responsive to the confirming and without authenticating the user within the payment application.