Would you be willing to share more about your experience with these companies? I have a client evaluating Twilio alternatives due to skyrocketing costs, and some of these companies are on the list.
We've used Twilio, Nexmo (now Vonage), and Plivo for years.
Twilio is still our go-to for US SMS.
Nexmo has great international deliverability but is more expensive than Plivo.
Plivo works fine when it works. When it doesn't, their support is horrible. Most times I don't even bother opening a ticket anymore. I just switch the customer to Nexmo.
I tried A2P 10DLC registration on Twilio when it first came out and our deliverability went to less than 50%. I quickly switched if off.
They're all going to start requiring A2P 10DLC registration for US SMS within a few months. It's going to be painful to get timely SMS delivered.
The companies I mentioned are substantially inferior in terms of engineering compared to twilio. Plus twilio is more transparent and trustworthy f.e. with porting out numbers.
Voxbone is a Russian cheaper twilio clone.
Plivo is an Indian cheaper twilio clone.
Bandwith is a disaster. You just need to get a single look at their control panel which they won't show to you unless you're a paying customer.
