[Ethereum] whether metamask can be used on cell phone browser

uPort has plans to support some deep-linking transaction signing like this, and it might make sense to port MetaMask to mobile and support app deep linking of this sort in the meanwhile. MetaMask does not currently have a dedicated mobile developer, but a community member had good success with an effort to start porting to mobile, which could absolutely allow for a mobile MetaMask to sign deep-linked transactions from other apps:

https://github.com/petejkim/metamask-mobile

He hasn't been able to continue efforts on the app lately, but it's close enough to warrant serious consideration about getting it running.

You shouldn't be using web3.currentProvider anymore. This is the old way. Do this instead:

if (window.ethereum) {
    web3 = new Web3(window.ethereum);
} else {
    // Code for HttpProvider remains unchanged
}
await window.ethereum.send('eth_requestAccounts');

See How to Connect Web3.js to MetaMask in 2021