In many cases, it is not possible to deposit funds for one bank into another bank's ATM. There are some occasions in which banks that share a common ATM network can allow customers of other banks to make deposits.
Federal regulations have certain laws set up regarding making deposits on bank accounts in ATMs not owned by that particular bank. Banks are required to provide a notice to their customers that funds deposited may not be immediately available, the funds must be made available no later than the fifth business day after the day of deposit, and the day of deposit is considered as the day that funds are removed from the ATM. In addition, if deposits are not removed from an ATM more than twice a week, then the ATM must state which days the deposits are considered received.
However, certain banks do not allow deposits to be made at other banks' ATM's at all. For example, Santander Bank only allows funds to be deposited at Santander ATM locations.