While using a flatbed or dedicated film scanner will yield best results, if you do not have access to a scanner, you can use your phone to perform some of the same functions. It is important to remember that images "scanned" by your phone are not going to be of the same high-quality you can achieve with a true scanner. Do not discard your original images or rely on these "scans".
Where scanning apps are best is in their ability to remove glare from your image and to make it fully square, even if your photograph is not taken directly straight-on. Each app does different things better than others - you may find yourself trying one or two and then deciding which is best for your needs.
Apps for iOS
Apps for Android
If you do not have a dedicated digital camera, you can still get decent photos using your cell phone.
Here are some tips and tricks to take good pictures with whatever camera you have, whether it is your cell phone or a digital camera.
Cell Phone Camera Tips