Around the early 2000s, phone companies began experimenting with sales and offering clients simple PBX systems based on open-source solutions. Typically, such a service included only essential features: IVR, call forwarding, call distribution, and a few others.
Initially, these simple PBX systems were relevant, but over time, users needed integrations with CRM systems, call tracking, and other capabilities that open-source platforms could no longer provide. Configuring basic features was also inconvenient: users had to call the operator's engineers each time.
During this period, OTT operators emerged, understanding business needs and specializing in selling additional options. Traditional telephone companies adopted successful practices from their competitors, and PBX sales transitioned to a new level.