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220-1201 Practice Question: A technician is troubleshooting a smartphone that…
A technician is troubleshooting a smartphone that can send and receive text messages but cannot make or receive phone calls. The device shows full signal bars. Which network setting is most likely misconfigured?
⚠ Common exam trap
The 220-1201 exam often tests the misconception that full signal bars guarantee voice call capability, but the trap here is that signal bars only indicate LTE signal strength, not the availability of a voice-capable network layer (circuit-switched or IMS).
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The device's preferred network type is set to 'LTE only' and VoLTE is disabled.
When a smartphone shows full signal bars but cannot make or receive voice calls while SMS works, the most likely cause is that the device is set to 'LTE only' as its preferred network type and VoLTE (Voice over LTE) is disabled. SMS can be carried over LTE via IMS (IP Multimedia Subsystem) or fallback to circuit-switched networks, but voice calls require either VoLTE or a circuit-switched fallback (CSFB) to 2G/3G. With 'LTE only' selected and VoLTE off, the device cannot initiate or accept voice calls because it lacks a circuit-switched connection and has no fallback path.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The device's data roaming is turned off.
Why it's wrong here
Data roaming specifically pertains to using cellular data services, such as internet browsing or app data, when a device is operating outside its home network's coverage area. It has no direct impact on the ability to make or receive standard cellular voice calls or send SMS text messages, which are typically handled by the voice network. Therefore, turning off data roaming would not prevent voice calls while allowing texts.
- ✓
The device's preferred network type is set to 'LTE only' and VoLTE is disabled.
Why this is correct
Modern LTE networks are primarily designed for high-speed data transmission. For voice calls, many networks rely on Voice over LTE (VoLTE) to carry voice traffic as data packets over the LTE network. If VoLTE is disabled, and the device is configured for 'LTE only,' it cannot fall back to older 3G (UMTS/HSPA) or 2G (GSM/GPRS/EDGE) networks for circuit-switched voice calls. This configuration effectively prevents the device from initiating or receiving voice calls while still allowing data services and SMS over LTE.
- ✗
The device's Bluetooth is enabled.
Why it's wrong here
Bluetooth is a short-range wireless technology primarily used for connecting peripheral devices, such as wireless headsets, speakers, or car kits, to a smartphone. Its operational status, whether enabled or disabled, has no direct bearing on the device's ability to establish or maintain cellular voice calls over the mobile network. Bluetooth operates independently of the cellular radio responsible for communication with cell towers.
- ✗
The device's airplane mode is turned on.
Why it's wrong here
Airplane mode is a setting designed to disable all wireless communication functions of a device, including the cellular radio, Wi-Fi, and Bluetooth. If airplane mode were enabled, the smartphone would be completely disconnected from the cellular network, preventing it from sending or receiving any cellular texts or making voice calls. This contradicts the problem statement that the device 'can send' (texts).
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1201 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1201 exam.