There are 4 primary options for cell phone "boosters", all with their own pros and cons:
1. Wifi calling - uses the wifi on your phone.
- Upside - included with most cell phone plans - just enable on your phone
- Downside - works well if you have NO signal or a reasonably strong signal. A very marginal signal will actually cause it to often not work at all. Carrier specific.
- Source/Instructions: Contact your carrier to confirm if WiFi calling is available. Follow the instructions below for enabling WiFi calling on your device.
- Apple iPhone: https://support.apple.com/en-us/HT203032
2. "Femto cell" device - small "consumer-class" devices that broadcast locally but get their connectivity via the Internet and are specific to a particular wireless carrier (Verizon, AT&T, Sprint, T-Mobile, etc).
- Upside - Cheap (~$250)
- Downside - Limited number of users, specific to 1 carrier, small range (30-40' radius)
- Source: Contact your carrier
3. "Micro cell" device - just like a femto cell, but an "enterprise-grade" device.
- Upside - Much higher user count (100+), medium range (75-100' radius)
- Downside - Specific to 1 particular carrier, and expensive (~$3000).
- Source: Contact your carrier
4. In-building Cell Repeater. Rebroadcasts a wide range of LTE signals.
- Upside - Carrier independent (as long as it covers the right frequencies for the carriers you're concerned about), no Internet access required. Similar coverage to Micro cell (75-100' radius), but multiple antennas can be deployed off of one booster, and a system of multiple boosters can essentially cover an unlimited area.
- Downside - requires substantial equipment/install investment (starting at ~$6000-$7500 and going up from there depending on the amount of area you're trying to cover), permanent antennas mounted inside/outside your building. Unlikely, but not useful if there is no repeatable signal at all (i.e. "No Service" even from outside the building).
- Source: Find a local installer (start at https://www.wilsonpro.com/)
Sometimes the cheapest/simplest solution is to switch wireless carriers. Every carrier uses different towers and frequencies, and regardless of what location you're considering, every carrier will have a different signal strength, especially once you go inside of a building (and particularly in block wall buildings and basements).