UPSC Prelims 2019 Q75: Science & Technology – Computer & Information Technology

UPSC Prelims 2019, General Studies Paper I · Science & Technology

With reference to communication technologies, what is/are the difference/differences between LTE (Long - Term Evolution) and VoLTE (Voice over Long - Term Evolution)? 1. LTE is commonly marketed as 3G and VoLTE is commonly marketed as advanced 3G. 2. LTE is data - only technology and VoLTE is voice - only technology. Select the correct answer using the code given below.

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Answer: (d) Neither 1 nor 2

Explanation

LTE vs VoLTE: Communication Technologies

Statement	Claim	Verdict	Detail
1	LTE = 3G, VoLTE = advanced 3G	FALSE	LTE is marketed as 4G, not 3G. VoLTE is voice service over LTE (4G data) - still a 4G technology, not 'advanced 3G'.
2	LTE = data-only, VoLTE = voice-only	FALSE	LTE carries data primarily (voice earlier via CSFB - Circuit Switched Fallback). VoLTE is voice over LTE data - it uses LTE's data channel to deliver voice as VoIP. VoLTE-enabled phones can carry BOTH voice and data simultaneously over LTE - not 'voice-only'.

Both statements are wrong. Answer: (d) Neither 1 nor 2.

Answer: (d) Neither 1 nor 2.

Why each option is right or wrong

(a) Incorrect. LTE is 4G, not 3G - statement 1 is wrong.
(b) Incorrect. VoLTE is not voice-only; it uses LTE data for voice-as-VoIP.
(c) Incorrect. Both statements are wrong.
(d) CORRECT. LTE is a 4G technology (not 3G), and VoLTE is voice-over-LTE-data (not voice-only) - both statements are wrong.

Key point

LTE = 4G data. VoLTE = voice over LTE data (VoIP over LTE). VoLTE-capable phones can carry voice + data on LTE simultaneously.

Remember

Both statements are wrong. LTE (Long-Term Evolution) is a 4G technology, NOT 3G. And VoLTE (Voice over LTE) is not voice-only - it delivers voice as VoIP over the LTE data channel, and VoLTE-enabled devices can carry voice and data simultaneously on the same LTE network.

Common mistakes

Confusing generational marketing - LTE (Long-Term Evolution) is 4G. 3G was UMTS/HSPA.
Assuming LTE was purely data - CSFB (Circuit Switched Fallback) let LTE phones use 2G/3G circuit for voice.
Not knowing VoLTE allows HD voice quality and faster call setup than CSFB.

Exam tip

Mobile evolution generations: 1G = AMPS analog voice. 2G = GSM/CDMA digital voice + SMS. 3G = UMTS/HSPA data + video. 4G = LTE (data) + VoLTE (voice over LTE). 5G = NR - IoT, ultra-low latency, mmWave. India: Jio launched with VoLTE-only from 2016.

Sources

TRAI - Mobile network technology publications
3GPP - LTE and VoLTE technical specifications

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