Yes, Coinomi can be used as a paper wallet. Provided you have taken the proper security measures, paper wallets are considered secure long term storage. They can safely receive deposits into their addresses at the same time as never being online in any way (except at the time you decide to spend the coins). To use Coinomi similarly as a paper wallet in the safest possible way, do this:
- Remove the SIM card from an Android device, factory reset it, and when turning it on never configure any kind of connectivity or Wifi.
- Download the APK installer from https://coinomi.com/downloads
- Transfer the APK to the device's internal memory and install it
- Run Coinomi, set up a new wallet backing up its recovery phrase on a piece of paper or other completely offline medium.
- Add the wallets of any coins you want.
- From those wallets, copy any number of "receive" addresses you want. You can generate new addresses by opening the "Receive" screen and selecting "... / New address"
- Once you're done, factory reset the device one more time.
Later, when you wish to spend the funds, simply reinstall Coinomi, restore the phrase, and bring the device online. You may wish to select "create a new wallet" in Coinomi once for every address, so that accessing funds from one will keep all others offline.
Must I do this every time I want to use Coinomi?
No. Online or offline, Coinomi never transmits your recovery phrase or private keys out of the device. The steps above are extra security measures in case you don't even trust the device itself, so you guarantee no data can be leaked. If you have good security practices, keep your device updated and free or malware, it's perfectly safe to use Coinomi while connected to the Internet.