Alpha preview of test net is already running at https://www.talking.im/network/. Full test net will be released by end of May.

TIM has deployed 36 test nodes on Amazon webservice (cloud) across the world. These test nodes generates transactions. Here, the Nodes are divided among five triangles / graph. These transactions are mined by the same nodes in respective triangles. Once the consensus is arrived then the winner node in blue announces the claim and this is pushed to blockchain miner in upper layer. Ultimately the Merkle root of block is added to a new block created on root blockchain. Alpha preview also displays what is current network state, how many partitions are created. Right now, 5 partition / triangle / graph is shown.