Yes, this is called "Local Activation" or "Dynamic Ad Insertion". Here's a little bit from Google about it:

It’s a strange feeling to be listening to a radio station in London or New York and suddenly hear an ad for the taco shop down the street from your house in Ohio. You are right on the money—this is often called Local Activation or, more broadly, Dynamic Ad Insertion (DAI).

Technologically, it’s less about the "radio station" and more about the "stream server" acting as a middleman. Here is how that local magic happens.

1. The Digital Handshake (Geotargeting)
When you press "Play" on a streaming app or website, your device sends a request to the station's server. This request contains your IP address.

IP Intelligence: The server uses a database to look up your IP address and determine your approximate location (City, State, or ZIP code).  

Device Data: If you’re using a mobile app, it might also share your GPS data or the "Home" ZIP code you used when you registered for the service.

2. The "Cue Tone" (The Invisible Signal)
On the station's side, the live broadcast isn't just one continuous audio file. The broadcast software inserts metadata tags or "cue tones" into the stream.

These tags are invisible to your ears but act like a "START AD HERE" sign for the streaming server.

When a tag hit, the server knows it has exactly 30 or 60 seconds to "cover" the live local ad playing in the home studio with something relevant to you.

3. Dynamic Ad Insertion (DAI)
This is the core technology. Instead of sending the exact same audio to all 100,000 listeners, the streaming server splits the stream for each individual user.

The Ad Stitcher: A specialized server (like AdsWizz or Triton Digital) receives the "start" signal. It looks at your location data and instantly picks an ad from a library of "Local Ohio" commercials.

The Stitch: It "stitches" that local ad into your personal audio stream in real-time.

The Seamless Return: Once the ad is over, the stitcher snaps you back into the live broadcast.

Why is this called "Local Activation"?
In marketing, Local Activation specifically refers to the strategy of turning a global or national brand into a "local" presence.

For example, if you're listening to a national sports broadcast, a brand like Ford might use local activation to ensure that instead of a generic "Buy a Ford" ad, you hear an ad for the specific dealership in your town. This makes the ad feel more urgent and relevant, even if the content you're enjoying is coming from halfway across the world.

Oddly enough, for about a week while I was listening to CFRB online, in Toronto, when initially tuning in I was hearing ads for businesses in London ON. I put it down to a glitch which eventually cleared up.