Launching an MVNO used to be a slow, expensive grind. You negotiated with MNOs, inherited someone's monolithic BSS/OSS stack, and then lived with it for years because switching cost too much. Every customization was a change order. Every new feature was a six-month conversation. That model is breaking down and the main reason is APIs. The Stack Is Finally Composable The fundamental shift happening right now is that telecom infrastructure is becoming composable. Instead of buying a monolith and hoping it covers your use case, operators are assembling stacks the same way a backend engineer assembles microservices: pick the best tool for each job, connect them via APIs, own the logic in between. This matters especially for new-wave MVNOs niche operators targeting specific communities, IoT-focused plays, B2B-only operators, or lean teams in emerging markets that can't afford the operational overhead of legacy systems. These aren't the old-school resellers.…