What a USDT network is
A network is the blockchain where your USDT is stored. USDT on TRC20 and USDT on BEP20 are worth the same, but to a wallet they are different coins: their addresses and fees differ.
TRC20 (Tron)
The most popular network for P2P in the CIS. The address starts with the letter T. Transfers take a couple of minutes, but the network fee for sending is usually higher than on BEP20 and TON.
BEP20 (BNB Smart Chain)
The address starts with 0x. Fees are low and transfers are fast. To send USDT from your wallet, you need a little BNB in it to pay the network fee; you can receive coins without it.
TON
The network built into Telegram: USDT on TON is convenient to keep in Telegram Wallet. The address usually starts with UQ or EQ. Fees are low and transfers take seconds.
The main rule
The address network and the transfer network must match. If you send USDT TRC20 to a BEP20 address, the coins may be lost. The bot always shows the network in the deal — check it before sending.