Primecoin is a cryptocurrency based on finding prime numbers. Identifying prime numbers plays a central role in cryptography. Primecoin's unique Proof-of-Work (PoW) consensus mechanism is able to increase transaction speeds and improve energy efficiency.
The network searches for special prime number chains known as Cunningham chains and bi-twin chains, which are of interest in mathematical research.

Telcoin is an Ethereum-based cryptocurrency that will be distributed by mobile network operators. Telcoin (TEL) plans on working with national telecom operators to distribute their currency. They hope that this distribution model will provide greater financial inclusion to un-banked communities, and will encourage cryptocurrency adoption. This is a similar strategy as MPesa, the mobile payment network created by SafariCom, that uses the telecom's provider's existing infrastructure to allow users to easily make payments with their mobile phones. Telecoin sees their platform as a complement to existing mobile money systems that will help drive cryptocurrency adoption.

Peercoin is the first Proof-of-Stake (PoS) cryptocurrency. It was created in 2012 and is one of the oldest and most reliable cryptocurrency networks in the crypto sector. The protocol was developed by Sunny King and Scott Nadel, both of whom are anonymous. Sunny King also created Primecoin and VEE.
Peercoin’s PoS consensus mechanism is now widely used in the blockchain space, and allows every network participant to be both a miner or an owner. The project is focused on creating a cryptocurrency platform that will be stable, secure, energy efficient, and distributed fairly.