Hey! I'd naturally recommend SignalWire (as one of the founders over there.)
We have a full messaging + voice + video APIs, including a Twilio-compatible API just for people who need to switch. We're backed by companies like Deutsche Telekom, T-Mobile, and Samsung so we know how to make telecom infra!
We're also the folks behind the open-source FreeSWITCH framework that powers companies like Bandwidth, Five9, Dialpad, Zoom Voice... maybe even your own company's PBX!
I mean, seriously. Twilio could allow (verified-ownership emails only) for the simplest possible email integration into twiml for the sole purpose of alerting and paging, etc.
No spam possible since it's only verified account-controlled emails. Basically sending email to yourself from within twiml.
But no. Instead they bought sendgrid and email integration is a complete abomination of a two-company, two platform, two accounts workflow that is fragile and fails all the time.
Unfortunately, I haven't found any. There are some hacky solutions that I've bookmarked over the years, but nothing reliable enough for a production service(s). At least that I've found.
Most "alternative" SMS services a simply a façade built on top of Twilio, with the markup to prove it.
