How many messages are you expecting to send? 300 - 500 USD/mo suggests hundreds of thousands of messages. Are you expecting thousands of users? If so, any chance that some of your users will pay for your service?
But when you start sending sms internationally, the costs can explode.
As memory serves, twilio charges about 10c to send an sms to Germany, for example.
I run a bootstrapped and somewhat successful monitoring saas and we literally keep a running balance of every users sms cost (as reported directly by twilio) and every user has a $ cap that resets monthly.
This estimate is also not taking into account carrier pass-thru fees, regulatory fees, phone number maintenance fees, etc. The idea that you can send 100K sms segments for a few hundred bucks just isn't true, even in the US. The pricing on these things gets way more complicated than what the marketing pages seem to indicate.
By way of example, my company is sending ~1.5M segments per month at a cost of a couple tens of thousands (I can't say exactly, obviously). This boils down to the fees that I mentioned, international examples that you gave, as well as the differences between SMS and MMS messaging where it's not always clear what counts as MMS (multi-byte encoding, anything with an attachment or URL, >N segments per message where N changes based on delivering carrier, etc.) It gets... Wonky.
Yes, this is what I am seeing. The more the regulation, fees and others as the users grow, it does not feel like viable option after some time. Maybe building an app and using push notifications would be better
I am expecting to send around 2000 messages a month as we scale. Yes, there are some paid tiers for enterprises but it is a long shot and is not immediate.
But when you start sending sms internationally, the costs can explode.
As memory serves, twilio charges about 10c to send an sms to Germany, for example.
I run a bootstrapped and somewhat successful monitoring saas and we literally keep a running balance of every users sms cost (as reported directly by twilio) and every user has a $ cap that resets monthly.