“I wanted to replace the SIM card at night, so I poked the small hole at the bottom of the phone with a needle for a long time. Only later did I realize that I had poked the wrong place. Did I break something?” This is a question that is repeated again and again and is quite understandable.
Modern smartphones have a highly integrated construction, and there are often several almost identical small openings and holes around the perimeter and the frame of the bottom of the device. If you don’t know which is for the SIM card, which is the microphone, and which is the speaker, it’s easy to make a mistake and even damage the device.
As an example, a modern premium phone will serve to explain what those “mysterious” openings are actually for.
There are usually two small openings on the top edge of the phone. One is the auxiliary microphone and the other is the audio output of the top speaker. The main microphone is almost always located at the bottom of the case, while the upper microphone serves to cancel noise during calls, record ambient sound and improve the quality of videos and conversations. The speaker itself is often not directly visible, but is hidden behind a very narrow grille or microslot.
What are the tiny openings on the smartphone frame for?
In older phones, there was often an opening at the top for an infrared sensor, which was used to control home appliances such as televisions or air conditioners. In newer models, that sensor is often moved to the camera module, next to the flash, to keep the phone’s frame visually clean.
On some models, an opening for air pressure equalization can be seen on the top or side edge. Its role is to quickly equalize the pressure between the inside and the outside environment. This is especially important in situations such as flying, staying at high altitudes or sudden temperature changes, where the difference in pressure can lead to deformations of the screen or the back cover.
On the side, some phones have additional openings that are part of a more advanced speaker system. In such solutions, there is a main speaker for conversations, while the auxiliary openings serve to form a sound wave that does not allow the sound during the call to be heard by the people around you and thus improves the privacy of the conversation.
On the bottom of the phone there are openings that most users are familiar with. This is where, from left to right, you usually find the SIM card slot, the microphone, the USB-C port and the main speaker. This is where the error most often occurs, because people try to remove the card by inserting a needle into the opening of the microphone. For this reason, manufacturers have been implementing protective solutions for years, such as a curved inner microphone channel, to prevent direct damage to the component.
There are also phones with almost no visible openings on the frame. In such models, the sound and sensors are located behind the micro-slits, within the camera module or under the case itself, which contributes to a cleaner design.
It is also important to know that most of these openings do not lead directly to the electronics. Behind them are waterproof and membranes that prevent the penetration of moisture and steam, rubber seals and other protective elements, which provide resistance to dust and water.
If there’s still any doubt about the construction or use of smartphones, it’s always a good question to ask before the needle ends up in the wrong hole.