As long as you do not need the number for big sites like Yahoo, Gmail, Facebook etc., those sites work very well for. I do not know for what he needs the number, but I wanted to point him to a free option.
Why don't you just use some of the free numbers available on the web. Just google for "receive free sms online" for instance and you will find a bunch of sites with free numbers.
I dont think the free numbers work for this. I can personally say i have helped this guy twice though and he does pay quick. Very easy to work with
Also theres two smartphone apps that work for ALOT of verifications. One is called Pinger, the other Textme. Textme seems to work better. Also, watching short videos on both earns you a couple (1-3) minutes to use for calls, and the quality is just as good as the phone. You could honestly just get a phone and only pay for 4G, use those apps and be fine lol I did it for a couple months w/ a tablet that I had 4G on, $13 compared to $80 really helped.