Earlyface

Make sure your VPN is up and running, I normally use premium ExpressVPN though, and ensure to use ONLY USA server address. You can use ip2location.com to confirm your IP location.

Now, visit https://textnow.com and click on the Sign Up link. Fill in your detail and click on the Sign Up button, in the next page, you will be asked to "Enter Your Area Code".

Simply log on to http://www.worldatlas.com/na/us/area-codes.html Scroll down to choose your preferred Area Code.

Input your Area code and tap on "Continue" button, then select your preferred USA phone number and click on "Continue" button. You should have your own US phone number within seconds without leaving Nigeria.

For more convenience you need to download TextNow mobile app. TextNow app is available for the Android OS, which is good for calls and messages push notifications. You can make calls and receive calls with it, you can also send and receive messages with it. TextNow is use for verifications on sites/features that do not support Nigeria and to chat and call the Foreign friends.

TextNow is available in Google Play Store, but Non-U.S resident can't download it easily there, even with the VPN, you may not be able to download the app from Play Store.

  Steps to download TextNow APK Version

Copy the Play Store link of TextNow Here.

Visit www.apps.evozi.com

Click/Tap on APK Downloader button and you will be redirected to another Site.
Paste the link of TextNow APK you copied in step one into the provided space and click on Generate Download Link button with the blue color background.
Click on the Green Download button on the next screen to download TextNow APK to your smartphone.
 For your time-saving, I have uploaded TextNow APK version on another server, you can easily download it here http://www2.zippyshare.com/v/eIS4N2WE/file.html

After installing TextNow APK on your Android device, connect your VPN Android version, then fire up the Textnow app to get started. You must be online to receive calls with TextNow free version.
You can view your calls and SMS messages history at the dashboard of your TextNow, once you're signed into your account.

TextNow Premium
Upgrade to premium is not compulsory, but to remove annoying ads, lock-in your number, and get call forward to your local number.

The Monthly fee is $2.99
The Yearly fee is $29.99
Warnings: Always ensure to use a US IP address while accessing your TextNow account.

This is where I dock the ship folks. 100% free US phone number in Nigeria, let me know if you like the offer. 

Source from http://nairaclass.com/forum/index.php?topic=1094.msg1130;topicseen#msg1130