Would someone please explain how Uber was able to do this:

Recently, my car would not start as I was preparing to go to work. I had never used Uber before and soon discovered I had to download their app to be able to schedule a ride.

I have an older android phone that did not have enough memory for the app.

I called their support number and after being disconnected twice, I researched how to use the service if you did not have a smart phone and filled out the required info on their web page. I was then instructed to text "GO to 827222" to complete the set up. I tested and nothing happened.

Gave up and got permission to work from home that day.

I also have a work phone that is an iphone and it was issued to me only a few months ago. Later that evening I had to contact someone using my work iphone and noticed there was a text with the word "GO to 827222".

Please explain how this text from Uber ended up on my work phone , How would Uber be able to know my work phone number which is not published? .