We send SMS to customers in multiple countries (several countries in Europe, US, Australia). Our customers use different mobile networks in their respective countries.
How can we test that our SMS sending partners can actually deliver messages to the networks our customers use?
We are using Simtest.it but we would like an alternative, as we have the problem that we never know who to blame when SMS aren't received in our test setup: did our partners screw up or is it a Simtest.it problem?
Clarification: The type of service I'm looking for is someone having separate mobile phones connected to computers in all my target countries. The service gives me these telephone numbers, I send an SMS there (possibly including some special token to identify the sender) and I get a report what SMS were received on what telephone number at what time.
Delivery notifications for arbitrary recipients (what Twilio is offering) are a different thing. We already get those from most of our SMS partners, and if you believe all of them you might just as well believe in Santa Claus. They may be reliable if you only send via Twilio to the US, but as soon as you go abroad all bets are off.