Payphones, Phone SIM Cards - data only vs Voice and SMS and Data

This topic has seen some changes in recent years/months.  Through Google searches I was getting a mixed messages of where and how to get SIM cards for phones. This is what I have concluded (subject to lack of thorough research).

• Bring your own phone, which is already registered for WhatsApp
• If you want a SIM with Voice and SMS, it is only available at the Airport.  It costs about 5,500 yen and comes with unlimited voice and sms and 1GB of data. We didn't get these as it had been a long trip, my daughter wasn't feeling well so we thought we'll get them later. 
• If you are OK with data (and no Voice and SMS) then you can get pre-paid data SIMS at various places.  The best value we found was 3GB for 3000 Yen or 10GB for 4500 Yen at the larger 7/11 or 7i Holdings. They are also available near the markets near Ueno subway station.
  You will need to scan in your passport to register online.
  

Pre-paid Data SIMS at 7/11. Take the card to the counter and they will give you the SIM. 

• There are payphones available pretty much everywhere. Follow these steps.
  https://www.tsunagujapan.com/how-to-use-a-japanese-pay-phone-in-10-steps/