- A
A portable Bluetooth speaker for transaction alerts.
Why wrong: A speaker is not needed; the phone's built-in speaker can provide alerts.
- B
A rugged case to protect the phone from drops.
Why wrong: While protective, a rugged case is not essential for POS functionality.
- C
A magnetic stripe reader that plugs into the headphone jack.
This is correct; such readers are designed for mobile POS systems.
- D
A high-capacity power bank for extended use.
Why wrong: A power bank is helpful but not essential for the POS function itself.
Question 197 of 1,020
Smartphone POS Terminal: Essential Card Reader Accessory
This 220-1201 practice question tests your understanding of mobile device accessories. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A small business owner wants to use a smartphone as a point-of-sale (POS) terminal for credit card payments. They ask which accessory is essential for this setup. What should you recommend?
Quick Answer
The answer is a magnetic stripe reader that plugs into the headphone jack. This accessory is essential because a standard smartphone lacks the hardware to read the magnetic stripe or EMV chip on a credit card, so the reader acts as a dedicated peripheral that captures payment data and transmits it to the phone for processing. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your knowledge of mobile device peripherals and their connectivity methods, often appearing as a straightforward hardware identification question. A common trap is confusing this with a built-in NFC chip, which handles contactless payments but cannot read magnetic stripes or chips directly. Remember the key distinction: for a smartphone POS terminal card reader accessory, the headphone jack or Bluetooth connection is the bridge, not the phone’s own sensors. Memory tip: “Jack for the stripe, tap for the chip” — a headphone jack reader handles the magnetic stripe, while NFC handles tap-to-pay.
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
✓
A magnetic stripe reader that plugs into the headphone jack.
The correct answer is C because a magnetic stripe reader that plugs into the headphone jack is the essential accessory for using a smartphone as a POS terminal for credit card payments. This reader captures the magnetic stripe data from the card and transmits it to the smartphone via the analog audio interface, enabling the payment processing app to read the card information. Without this reader, the smartphone cannot physically read the magnetic stripe, which is the most common method for swiping credit cards at a POS.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A portable Bluetooth speaker for transaction alerts.
Why it's wrong here
A speaker is not needed; the phone's built-in speaker can provide alerts.
- ✗
A rugged case to protect the phone from drops.
Why it's wrong here
While protective, a rugged case is not essential for POS functionality.
- ✓
A magnetic stripe reader that plugs into the headphone jack.
Why this is correct
This is correct; such readers are designed for mobile POS systems.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
A high-capacity power bank for extended use.
Why it's wrong here
A power bank is helpful but not essential for the POS function itself.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The 220-1201 exam often tests the distinction between essential accessories for specific functions versus general-purpose accessories; the trap here is that candidates may choose a power bank or rugged case as 'essential' for business use, but the question specifically asks for the accessory required to enable credit card payments, which is the magnetic stripe reader.
Detailed technical explanation
How to think about this question
The magnetic stripe reader uses the headphone jack's analog audio input to convert the magnetic flux changes from the card's stripe into audio signals, which are then decoded by the POS app using specific frequency-shift keying (FSK) protocols. This method is standardized for mobile POS systems and does not require Bluetooth pairing or Wi-Fi, making it a reliable and low-cost solution. In real-world scenarios, businesses often pair this reader with a tablet or smartphone running a payment app like Square or PayPal Here, which processes the transaction securely via encrypted data transmission.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 220-1201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this 220-1201 question test?
Mobile Device Accessories — This question tests Mobile Device Accessories — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A magnetic stripe reader that plugs into the headphone jack. — The correct answer is C because a magnetic stripe reader that plugs into the headphone jack is the essential accessory for using a smartphone as a POS terminal for credit card payments. This reader captures the magnetic stripe data from the card and transmits it to the smartphone via the analog audio interface, enabling the payment processing app to read the card information. Without this reader, the smartphone cannot physically read the magnetic stripe, which is the most common method for swiping credit cards at a POS.
What should I do if I get this 220-1201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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.
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