CHICAGO (CBS) — From the North Side to Lake Michigan to downtown, Chicagoans regularly complain on social media sites and cell carrier blogs about certain spots where cell phone service is spotty at best.

Among the complaints they have lodged are:

“I’m noticing a couple of very annoying dead zones (one being near the Armitage Brown Line stop).”

“Kimball Brown Line stop Lawrence and Leavitt. Anywhere around the Bryn Mawr Red Line.”

“Service overall is pretty spotty on the lakefront.”

“When I’m on the 135 bus from Michigan/Wacker to LaSalle/Wacker it’s almost dead. I still have bars but nothing loads until we turn down LaSalle.”

Although all major carriers’ maps show coverage citywide and websites like WhistleOut note that coverage “is generally excellent” all over the Windy City, people still can’t seem to connect whenever and wherever they want.

“Most of my work building is also a total dead zone for all cell service,” one local resident complains.

WhistleOut identifies where and why dead spots exist in a city like Chicago. For instance, they can happen between or inside buildings, on trains, under train tracks and be impacted merely by the fact that nearly three million people live in the city.

In addition, the Federal Communications Commission (FCC) explains that dead zones can occur if large objects come between you and the cell tower. Severe weather situations like wind and snow can also create dead zones.

There is a way to test your cell signal strength on the fly. CBS 2 Investigative Intern Brody Ford tried it out and checked out several spots in the Loop, River North and along the lakefront, using his Samsung Galaxy S7 on a 4G network. He discovered seven spots where signal strength was below average or weak:

• The ground floor of Block 37
• The Jackson Pedestrian Tunnel between the Red and Blue lines
• Outside the Fisher building at the corner of Dearborn and Van Buren
• 7th floor of the DePaul building at Wabash and Jackson
• The lobby/bar and the 10th floor of the Blu (Aqua) Hotel and Wacker and Columbus by the Chicago River
• His desk inside WBBM-TV

All major wireless carriers have ways to report any troublespots you find. AT&T and Sprint have apps that let you pinpoint problem areas. Verizon offers some tips to improve connections, including using Wi-Fi for data and calls, when available. T-Mobile urges its customers to sign a petition so municipalities will let the carrier make network improvements.

MONDAY AT 10: Technology designed to make it easier to pay for parking doesn’t deliver guaranteed peace of mind. CBS 2 Investigator Dorothy Tucker uncovers why payments aren’t being recorded, and how many tickets the city has had to throw out.