[toomuchtodo]

You are unable to spoof SMS numbers. Twilio has documentation on this if you'd like more info (experience: I tried, so I could SMS birthday messages to my contacts without remembering, but having it look like it came from me).

[adrianpike]

You're absolutely able to spoof SMS numbers from a technical standpoint, but you'll have to go straight to an SMSC or aggregator that lets you do it.

I haven't checked in years, but we had to write an SMPP library to pull it off. That sucked.

[toomuchtodo]

I should have qualified my statement.