The earliest versions of the Bluetooth protocol enjoyed a maximum range of roughly 33 feet, so if you wanted to use your Bluetooth device from a greater distance, you were out of luck. The newest version of the protocol, Bluetooth 4.2, can theoretically extend to 200 feet or more, but as with any wireless networking technology, the standard's theoretical maximum is constrained by the environment.
Align Your Specs
The original 4.0 or current 4.2 standard specifications do not, in theory, include an upper range limit, with the power and Bluetooth protocol in the weaker of the two connected devices setting the practical limit on theoretical range. If one device operates at the 4.2 standard with enough power to transmit 1,000 feet, but the other device is an older Bluetooth headset with a 33-foot range, the max distance between the two before the link fails is still just 33 feet. If your weaker or older devices supports Bluetooth upgrades, update it to the most recent version the hardware supports to eke out incremental improvements between protocol versions.
Avoid Physical Barriers
Because Bluetooth -- like Wi-Fi -- relies on two-way radio communication to work, any obstacle in the line-of-sight between the two connected devices serves to limit the effective range of the connection. For example, a Bluetooth signal travels farther in an open meadow filled with flowers and butterflies than it does in a concrete-and-steel office building. Dense objects between the devices degrade signal quality, so removing those barriers will improve the range of the connection. An act as apparently trivial as opening a steel door can open a room to Bluetooth signal that might otherwise have been blocked!
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Repeat the Signal
Deploy a Bluetooth repeater -- these devices serve as a middleman between the two paired devices. The repeater must be within range of the least powerful device, but by using the repeater, the least powerful device gets a boost. For example, a headset with a 33-foot range connected to a repeater with a 1,000-foot range, will effectively enjoy a 1,000-foot range. This solution isn't practical for in-the-moment or casual use, but for environments with fixed infrastructure, like an apartment building or home office, repeaters may prove useful.