Deex Exchange in partnership with the Cryptomat project has implemented special software for Android-based smartphones that allows to connect cryptocurrency exchangers. OTC platforms and cryptocurrency exchange services can use it to place their liquidity and implement secure p2p cryptocurrency exchange on the blockchain with smart contracts.
Read more here - https://deex.blog/en/news-deex-en/do-you-want-to-have-your-own-mobile-exchanger/