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What makes it possible for me to communicate with someone in another city when my phone can only reach the modem / wifi networks that are within 50 meters?

The signal may be sent between multiple destinations before reaching the final destination / end point, but I assume the first destination is still more than 50 meters away.

user48054
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    When you make a cellphone call, your phone is not communicating with a WiFi router (whose distance from your phone is measured in meters). Rather, your phone is communicating with a commercial cellphone tower (whose distance from your phone is measured in kilometers) . – Richard Lyons Mar 07 '20 at 11:11

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This question, having a physical and network rather than mathematical nature, is close to being off-topic, but for your convenience let me put an answer for it.

Making a phone call is traditionally a communications network operation. But recently IP telephony over computer networks (internet) also emerged and furthermore GSM (mobile cellular) systems are so much intermingled with internet that the traditional medium seems to have blurred boundaries.

Making a traditional phone call using your GSM cellular phone, involves accessing an operator base station (BS) closest to your location. Base Stations, work at 900/1800 MHz, ranges and can be reached at as low as about -110 dB signal levels. Therefore, your phone can reach a BS about a 5/10 kilometers away in free space and less than a km in city areas. Once it's reached, remaning connection to other cities etc., is powered and handled by the BS network itself. Your phone is only required to reach the closest BS.

Wi-Fi is term used to denote wireless internet access point, that enables internet capable devices to wirelessly connect to internet. It may be at your home, office or airport, operating at 2.4 (or recently 5) GHz. It's signal output power level is low, therefore it can be reached within a hundred or less meters for fast / reliable connections. Once you access a wifi, the remaining communication is powered by Wi-Fi adapter / router device and your device is not involved.

As another option, you can also make an IP phone call using WhatsApp, Skype etc with your smart phone-computer combo. Then it's either accesing the closest (and allowed) Wi-Fi access-point at home/office or it may also be doing it through the GSM BS internet using its mobile data feature...

Fat32
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  • I don't know much about this, I try to understand so thank you for explaining.

    So if the phone has the ability to send / radiate a wave several kilometers to the nearest tower, why can't it use the same technology to communicate back and forth with similar modems / antennas within the same distance for networking purposes (wifi) ?

     – user48054 Mar 08 '20 at 11:47
  • Very good question... The cell phone uses higher transmit power to communicate with GSM BS tower, than it uses to reach home wifi modem. This will affect the battery time. We expect long wifi connection compared to long phone talks. Also the design pupose of wifi modem is to be used within a home local area, hence it needn't transmit that high power. There are other details as well, that wifi communication should be fast and reliable needs some minimum signal levels maintained. – Fat32 Mar 08 '20 at 12:22
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https://imgs.xkcd.com/comics/wifi_vs_cellular.png

For those of us who remember dial up modems it is really striking that cellular can be faster and more robust than wifi.

Knut Inge
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