Ask HN: Good alternatives to Twilio for SMS delivery?

My webapp is sending several thousands SMS via Twilio per month and we ran into huge problems with Twilio a couple of weeks ago. Bascially many SMS where marked as "sent" but have not been "delivered" to our users, because one of their upstream providers started to have issues with non-GSM encoded SMS.

Twilio did not proactively inform us about this issue, but instead we found out about it after several users told us that they do not receive SMS from us anymore. Twilio also keeps charging us for these "sent" but not "delivered" SMS, even though we got into contact with their customer service.

I like Twilio but this is unacceptable to me. I actually do not need any phone API but just need to reliably send SMS. So we are looking for a new provider. It is important that this provider can send SMS to the US but also all European countries.

Has anybody else good alternatives to Twilio?