CallAnnie seems to use iOS built-in "neural"/AI functionality/API, which does processing on-device (rather than in-the-cloud), which requires your phone's SoC to have the gubbins for accelerating those computations (basically a mini-TPU): https://machinelearning.apple.com/research/neural-engine-tra... - Apple says you need an A11+ for iPhone (since iPhone X), or A12+ for iPad, and M1+ for macOS.
