Comment by pogue

Businesses who validate phone numbers often use an API (like Twilio Lookup or one of the many, many other services) to check for VoIP numbers and automatically reject them most of the time. Unfortunately, lots of VoIP is used in fraud, so the will often just reject them out of hand. If this is happening, none of the other "virtual" number services will work and you'll want to get a cheap eSIM.