USDT is a token issued by the company Tether. It mostly follows the price of the US Dollar. The token exists officially on some blockchains, and unofficially on several others.
Adding a USDT wallet
Like other tokens, you add USDT by pressing the "+" button and selecting "add tokens". You can then choose which on network you want to use USDT. For example if you want to receive USDT on the Ethereum network, choose "Ethereum" to list all tokens on that network. Finally, select USDT on the list. Depending on the network it may be called Tether, TetherUSD, USDT or some other variation.
How do I send/receive USDT?
To receive USDT use the "receive" Tether address as normally. Make sure that the correct network is used. If withdrawing from an exchange on the Solana network, use your Solana USDT address to receive. If withdrawing on the Ethereum network, use your Ethereum ERC20 token address and so on.
Likewise, when sending to an exchange or external wallet, check that they can receive on the network you're sending from. If for example you have USDT on Ethereum, it cannot be sent in any other network. Triple check that the receiving wallet accepts the network you're sending on. Sending on the wrong network can cause irreversible loss of funds.
USDT transfer fees
Like with other tokens, USDT itself cannot be used to pay gas fees for its transfer. Gas fees must be paid with the native coin of the network you're transacting on (ETH on Ethereum, TRX on Tron and so on).
The reason Coinomi cannot automatically convert the required base amounts and pay for fees, like for example online exchanges do, is the very reason it's safe: We are not custodian to your funds, so we cannot authorize that exchange for you automatically. Online exchanges own the private keys of your wallets, and also have ready made markets for those exchanges.
USDT on Omnilayer?
Essentially, Omnilayer is a dedicated BTC wallet that can hold tokens. As of September 1st 2025 Tether (the company) ended Omnilayer support (source). This means Omnilayer USDT tokens can no longer be transferred or redeemed.