Twilio and MessageBird have the same customer. Someone who is using Twilio could reasonably convert faster than someone who doesn't use any api-based telephony integration. You skip the step of convincing internal teams that you should do this in the first place.
At ZenPayroll we didn't just ignore people on ADP, Paychex, Intuit, etc. That would be nuts!
If you're trying to reach "people who integrate with telephony APIs" the Twilio conference is…the perfect place to find them!
re: spending time/money/effort to come to conferences:
1) They are networking events.
2) They are paid for by companies so employees aren't by default that invested.
3) It's not a lot of effort. Employees like going to conferences. You meet people. It's paid for. You don't really have to do anything. It's a workation for most.
As for retention, much of Twilio is mostly a commodity. MessageBird came to the US and started a price war, which is really what you're competing on. Switching SMS APIs isn't the same as, say, switching off of SalesForce.