Voice commerce—transactions conducted using voice-activated AI assistants—has transitioned from experimental technology to a global retail channel influenced by linguistic diversity, cultural trust, digital infrastructure, and AI adoption levels. This study analyzes voice commerce usage across North America, Asia-Pacific, Europe, and the Middle East using theoretical frameworks, consumer behavior modeling, and hypothetical datasets. Results show adoption is highest in digitally mature markets with strong smart-home penetration, while emerging markets adopt voice commerce through mobile-based assistants rather than smart speakers. Key adoption drivers include convenience, personalization, hands-free usability, and AI integration, whereas barriers include language accuracy, privacy concerns, low device ownership, and limited regional content. A multi-layer adoption framework is proposed integrating cultural voice identity, device ecosystems, and policy compliance.