The time to transmit the ACK back to the sender is a function of the phone lines, as opposed to the modem's speed, and is typically about ​1⁄10 of a second on short links and may be much longer on long-distance links or data networks like X.25. For a protocol using small packets, this delay can be larger than the time needed to send a packet. For instance, the UUCP "g" protocol and Kermit both use 64-byte packets, which on a 9600 bit/s link takes about ​1⁄20 of a second to send.