Hi! iPhone fax apps are generally optimized to work well on both Wi-Fi and mobile data connections. This makes them reliable even when you’re commuting or traveling and don’t have access to a stable office network. Most apps automatically optimize file sizes and resend faxes if there are temporary connection issues. To learn which apps perform best on mobile networks, I recommend checking https://venturebeat.com/business/5-best-iphone-fax-apps-send-documents-from-your-mobile-in-2025 for a full comparison.