Nice tutorial on tying these pieces together!

Title is misleading. Heroku is genuinely $0.00, but after the trial period Twilio goes to $1/month (for the phone number reservation) and $0.01/minute for voice calls. A bit like saying "Big-Screen TV at Best Buy for $0.00", because, after all, you can return it for a refund within 30 days.

@korussian: Tropo is a nearly identical service that offers local numbers in 40 other countries. See their FAQ: https://www.tropo.com/docs/scripting/faq.htm They will also host basic scripts on their own site (Python/PHP/Javascript/Ruby), so you can do without Heroku altogether. And the best part is, they cost three times as much ($3/month + $0.03/minute)!