There are exactly two ways to chat with a local LLM from your phone. Picking the wrong one for your situation is the most common mistake in this whole hobby. More common than picking the wrong model, honestly, because people pick the setup that sounds cool instead of the one that fits their life.
Setup one: everything on the phone. Install a free on-device AI admin app like PocketPal AI, Android or iOS, download a GGUF model over wifi, chat. Fully offline after the download. Nothing leaves the device. This is for travelers, the privacy-minded, anyone who wants AI in airplane mode. The limits are the phone: small models only, noticeable battery drain, multi-gigabyte downloads you do not want to do twice.
Setup two: the phone as a window. Ollama, LM Studio, or Jan on a home computer, and you connect from the phone with a local LLM management app for iOS and Android. The model runs on the big machine, the phone shows the conversation. Bigger models, longer chats, shared household or office use. The limits flip: you need an always-on computer, and it only works when you can reach your network.
Most people should start with setup one. Twenty minutes, costs nothing, teaches you what local models feel like. Move to setup two when you can name the phone's limits: you want a bigger model, you want the family on it, you want it running while you are away. A mobile admin app for your local AI stack earns its keep in setup two. Less so in setup one.
Whichever you choose, the model file is the decision that matters. Our database tracks 200 open-weight models with the hardware each needs, phones included. Best local LLM for a phone is its own question. Want private AI for the whole company, phones and all? I do private AI setup for businesses at privateaiagent.fyi. Your data never leaves.