Scrambling Outgoing Phone Number

You might also take a look at this app:

https://itunes.apple.com/us/app/burner-disposable-phone-numbers/id505800761?mt=8

It generates "disposable" phone numbers. I haven't tried it myself but the reviews seem ok.

That's called 'spoofing' and it's against the law. you can completely block your number from appearing, or you can let it display. You could also use a 3rd party service like Google Voice, which can send your Google Voice number instead of the numbe of the phone you're holding in your hand. I use that for work related calls on my iPhone (and previously on a land line as well). It allows for individual contact blocking, call screening, filters, schedules, etc. Nice to have, and a free service in the US.

Sending a number that doesn't belong to you, though, is against the law.

No. That would be illegal.

You mean changing it to a different number (i.e., scrambling), or do you mean blocking the number from being displayed at all?

I want to make a phone call to someone where I don't want them to have my phone number...

Call from a pay phone, if you can find one.

Figured so but sometimes the most obvious answers aren't, at least for me. 😉

Another option... call from a demo phone in a phone store, i.e. ATT, VZW, etc.