F-Oncall

"F-Oncall is a client specifically designed for Oncall V22 or later versions, exclusively for iPhone.
It leverages Wi-Fi or 5G/4G/LTE connections, enabling users to make and receive calls as well as send instant messages.
It supports push notifications, allowing users to receive calls and messages even if the app is force-closed.
By accessing the iPhone's contact list, F-Oncall offers a user-friendly interface for efficient communication management. It supports multiple calls, enabling users to switch between calls, merge and split calls, and perform attended and unattended transfers. Additionally, it supports video conferencing with MCU (Multipoint Control Unit) support.
F-Oncall prioritizes security and incorporates advanced settings for secure call signaling and audio encryption.
The application supports high-definition video calls up to 1080P using H.264 and VP8 codecs, ensuring high-quality audio calls. Supported codecs include G.279, G.711a/u, Opus, AMR, AMR-WB, G.722.1, iLBC, GSM, and SPEEX-WB.
F-Oncall supports group chats and allows the sending of voice, video, images, files, and more."