We (Twilio) are also only charging for successful delivery. Failures to not incur any billing. Retry is (currently) on the customer to implement, but since we don't charge for failures, that doesn't affect cost.
Yes, we're charging per-minute fees, but for US, at least, it's sub-1-cent, and with my testing so far, I haven't seen it go more than a couple minutes per page for something fairly complex, and that's worst case.
Yes, we're charging per-minute fees, but for US, at least, it's sub-1-cent, and with my testing so far, I haven't seen it go more than a couple minutes per page for something fairly complex, and that's worst case.