Ask HN: How to do transactional SMS as a bootstrapped or startup company?
Ok, first let me classify companies that offer these services.
Tier1:  Twilio, Plivio, MessgBird, Vonage, Amazon SNS
Tier 2: Alternatives for these 
Tier 3: More Alternatives, but geo based and also focussed on bulk SMS as primary offering<p>Now, ì do not want to get into Tier 2 also as the API approach ad DX is not available compared to how it is with Tier1. Also I don’t want to risk my customers phone numbers with providers who do not have good support and privacy handling features.<p>There are couple or more apps that I am building where I like the simplicity of SMS. I don’t have to request for push notification permissions, I do not need an app on the stores to push relevant info and updates. 
Most basic User signup. If user does not want to use the phone, then maybe the service is not for them. And then occasional updates on Direct messages on the platform. (Order completion, delivery instructions, Direct Messages from users etc.) I see most of these as small messages only if they ever did take actions on the platform.<p>However, based on my initial calculations, even with 1000 users signing up. 
Allowing SMS code input and DM messages or info messages, these can reach a number of close to 300 to 500 Euros or Dollars monthly.  This is including alpa numeric sending options. Where I do not allow messages to be replied back.<p>When I started  programming SMS was the cheapest option. Now I feel it has become expensive
However I still see small and big companies using these options. 
1. Are there other alternatives I am not seeing?
2. Since my volume of push and sending is low, I do not want to ask users push notification and scare them away
3. What other options can we see here.