The Omni Hotline App works on both mobile data and Wi-Fi. However, the speed of the app depends on:
Network signal strength
Network signal strength refers to the signals received by a mobile phone from a cellular network. Depending on various factors, such as proximity to a tower, any obstructions such as buildings or trees, etc. This signal strength will vary. Most mobile devices use a set of bars of increasing height to display the approximate strength of this received signal to the mobile phone user. Traditionally five bars are used.
Network bandwidth refers to internet speed which is your (allocated) bandwidth. Bandwidth is the amount of data that can be sent to you, usually measured in seconds. For example, 5 Mbps would mean that you can receive up to 5 megabits of data per second. However, this is influenced by proximity to the modem, online traffic, and connection type