One of the less heralded, yet most crucial, metrics when it comes to customer satisfaction with wireless service is network latency, which is defined as the time it takes for a source to send a packet of data to a receiver. Latency is typically measured in milliseconds, and the lower the latency (the fewer the milliseconds) the better the network performance. Starting this month, FierceWireless and its partner OpenSignal are taking a closer look at the network latency speeds of the Tier 1 U.S. wireless carriers. During the month of October, T-Mobile US' (NYSE:TMUS) LTE network showed the lowest latency figures, just beating out the latency speeds of AT&T Mobility (NYSE:T), Verizon Wireless (NYSE:VZ) and Sprint (NYSE:S). For the first report, click here.