Comparison of VoIP and PSTN Services by

Statistical Analysis

Mr. Amir Sinaeepourfard Faculty of Information Technology

Multimedia University

Selangor, Malaysia

a.sinaee@ieee.org

Mr. Helmi Mohamed Hussain Faculty of Information Technology

Multimedia University

Selangor, Malaysia

helmi.hussain@mmu.edu.my

Abstract— One of the most common ways, where anyone can

communicate with each other very easily, and instantly, is,

of course, the voice exchange. Public Switched Telephone

Networks (PSTN), and Voice over Internet Protocol (VoIP) are

common ways of transferring voice communications by using

telephone network. These two ways have their own strengths

and weaknesses. The two major positive points of the PSTN are

reliability, and stability. One of the drawbacks of the PSTN is

that it has complex connectivity. The VoIP strengths are

cheaper in costs compared to PSTN, less usage of cable,

user-friendly, simple connectivity, and variety of services.

On the other hand, the biggest challenge of VoIP is frequent

disconnects of voice communication. In this paper, a survey is

being performed on a selected group of people to understand

the quality differences between PSTN, and VoIP. This paper

shows that the Quality of Service (QoS) of today’s VoIP is not

good enough but users still continue to use it. However, this

survey is also trying to find ways on how to improve existing

QoS of VoIP. Plus, it points out what type of users prefers to

utilize by using PSTN or VoIP.

Keywords- PSTN ; VoIP; ADC; DAC; QoS; Statistical

Analysis

I. INTRODUCTION

There are two different architectures of voice

communication existing around the world today, which are

PSTN, and VoIP. Traditional telephony network is

implemented by PSTN architecture [1]. The VoIP or Internet

telephony connects to the Internet, and then transfers the

voice from sender to receiver. To complete the whole cycle

of transferring data between the sender, and the receiver,

firstly the sender converts voice to binary code data, and puts

this data over the Internet, and after that, the receiver gets the

data, and then, reconvert it again to voice as shown in

Figure 1 [2]. It shows how the voice transfers, and uses

Analog to Digital Converter (ADC), and vice versa that is

Digital to Analog Converter (DAC).

A. Pros and cons of the VoIP and PSTN

In order to compare PSTN, and VoIP technologies more precisely, researchers refer to many scientific papers. The great things about the PSTN are its reliability, stability, and accessibility, but the downside is that it needs more cable to connect devices to each other.

One of the benefits of VoIP is that the Internet spreads swiftly throughout the world [3]. Besides that, the VoIP call provides low cost call especially for long distance [4]. Plus,

lots of features are attached to VoIP such as call management. These rich features can be applied easily by users [5]. Last but not least, it is a piece of cake to connect architectures of PSTN, and VoIP together in today’s world. As a result, it can be seen that the VoIP technology is dominating the world very soon unlike the majority of the new technologies that evolves slowly. On the other hand, packet lost remains a major problem of the VoIP services [3].

B. Barriers of the voice quality

The quality of the VoIP technology is the biggest challenge in this world of technology. Latency (or delay), jitter, and packet loss are negative effectiveness elements to change the voice quality of VoIP technology. Latency, or delay, is defined as the average “travel” time it takes for a packet to pass through the network, from source to destination. Jitter is defined as the variability in packet arrival at the destination. Packet loss is the percentage of undelivered packets in the data network [6].

The remainder of this paper is organized as follows: Section II describes related work. Section III elaborates paper’s approach for observation, organization, and interpretation of data. Section IV provides results for the approach. Section V presents conclusions of this survey.

Fig. 1. Transmission Technology of the VoIP

II. BACKGROUND OF STUDY

When a new technology is invented in the world, many

scientists research, and make comparison between new, and

existing technology. Consequently, when Internet telephony

was added to daily communication, lots of papers were

written about PSTN and VoIP. The researcher made

comparison by estimation of electrical consumption, service

payment, and different qualities, and architectures [6-9].

The purpose of this survey is to study, make comparison

between PSTN and VoIP, and derive results based on

2011 IEEE Student Conference on Research and Development

978-1-4673-0102-2/11/$26.00 ©2011 IEEE 459

technology user’s opinion. This type of study can help

researchers to get feedbacks from users, understand the

usage pattern among users, and thus, make better solutions

for this technology.

III. APPROACH FOR OBSERVATION

This study is aimed to observe how a group of diverse people in terms of age, gender, field of study, or nationality vote to choose quality between the two types of voice communication technology. The obtained results show how many people can accept the VoIP technology, and apply this in their daily communication. Besides that, this analysis is also looking on how to improve quality of the VoIP technology.

A. Experimental Environment

This survey selected Multimedia University in Malaysia as the venue for this survey. One of the main reasons for choosing this venue is that the university comprises lots of foreigner, and local students that show high potential usage of variety model of communication among family, and friends. This study was conducted randomly on seven hundred fifty students. The distribution of students is shown as Figure 2.

B. Questionnaire form

The questionnaire form has multiple questions, and

answers that show the comparative QoS of the PSTN, and

VoIP. The students answered each question. The questions

are divided into two parts, which are shown as below:

Part I:

1) What is the speed of your Internet connection currently?

2) Do you have information about VoIP?

3) When you want to talk with someone especially who

lives in overseas, which kind of phone connection are you

using currently?

4) If you use the Internet telephony to call any person, do

you encounter frequent disconnection?

5) Which kind of the phone connection do you prefer to use

at anytime?

6) Did you use video call before when you had the best

quality of the voice communication?

Part II:

7) Which software of the phone connection have you used

so far?

8) Which service provider(s) of the Internet connection

have you used in Malaysia?

9) Which software had the best quality so far?

10) Which service provider had the best quality so far?

The Part I contains purely the analysis section in this study. The Part II does not show the analysis but it is designed to collect more information about the situation of the user connection to make better conclusion about the result in Part I.

IV. MEASUREMENT-BASED APPROACH

In this study, statistical method is being applied on the random sampling to collect data, analyze, conclude, and to make predictions for future trends.

A. Analytical results

The Measured Experiments results are arranged by Tables I, II, III, IV, V, and VI.

TABLE I. PERCENTAGE OF STUDENTS FOR QUESTION 1

Question 1 Answer

<= 2 Mbps > 2 Mbps Total

Percentage of counting votes 70 % 30 % 100 %

TABLE II. PERCENTAGE OF STUDENTS FOR QUESTION 2

Question 2 Answer

Yes No Total

Percentage of counting votes 32 % 68 % 100 %

TABLE III. PERCENTAGE OF STUDENTS FOR QUESTION 3

Question 3

Answer

Internet

telephony

Normal

telephony line

Telephony

card Total

Percentage

of counting votes

46 % 38 % 16 % 100 %

TABLE IV. PERCENTAGE OF STUDENTS FOR QUESTION 4

Question 4 Answer

Yes No Total

Percentage of counting votes 64 % 36 % 100 %

TABLE V. PERCENTAGE OF STUDENTS FOR QUESTION 5

Question 5

Answer

Internet

telephony

Normal

telephony line

Telephony

card Total

Percentage

of counting votes

48 % 38 % 14 % 100 %

TABLE VI. PERCENTAGE OF STUDENTS FOR QUESTION 6

Question 6 Answer

Yes No Total

Percentage of counting votes 62 % 38 % 100 %

The Measured Experiments produce some results written as below:

1- Regarding to Table II, and III, it is surprising to find out that majority of 46% of students use the VoIP service in their daily lives without knowing what the VoIP is.

2- Regarding Table V, 48% of the students vote that the Internet telephony is the preferred option when it comes to choosing the method of voice communication especially in long distance communication. Plus, the telephony card is also a type of the VoIP technology. Nevertheless, 64% of the students mention that the Internet telephony faces frequent disconnection regarding Table IV.

3- When this study is analyzed in greater depth about the problem of the students, who had frequent disconnection in the VoIP service, it is being found that almost every student has problem with Internet speed rate that is not enough for voice communication. Although, a small amount of these students had the suitable speed rate of the Internet connection, this problem is still happening. After further investigation about this phenomenon, it is shown that these students do not have much information on how to use this technology. For example, when a student wants to establish a voice connection with the others, the student also uploads or downloads huge files at the same time. By doing this, the student does not know that it will greatly reduce the amount

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of bandwidth. Throughout this study, it can be seen that there are many similar phenomenon occurring as a result from the inadequate knowledge on the usage of technology.

4- The study shows that sometimes the speed rate of the

Internet connection is adequate on the sender side, but that

is not the case on the receiver side. The reason is this is

a two-way communication. Both sides need to have

adequate speed rate of connection for optimum results.

5- The majority of the students, who utilizes the VoIP so far,

like to use voice and video at the same time. It is clear

when users use voice and video together needs more

bandwidth.

6- This survey shows the majority of local users prefer to

use PSTN because it is more affordable, and accessible.

In contrast, foreigner users like to utilize VoIP due to

affordable cost, and variety settings for call, and video

management.

V. CONCLUSION

The surveyed results from this study are being observed,

analyzed, and evaluated carefully. It looks like local users

like to use PSTN. That is due to the land line has affordable

cost, and more reachable. By the way, foreigner users want to

connect with VoIP because it is more economical to use for

long distance communication, and there are additional

services such as video connectivity, and further functions.

Moreover, it seems users continue to use the VoIP

even though there are frequent disconnections.

A few suggested solutions to improve QoS of VoIP are

users need to collect further information, and understand the

basic requirements of the VoIP before using it. There is

still a lot of room for improvement on existing QoS of VoIP

technology, and definitely, more researches to be done in the

day to come.

REFERENCES

[1] R. Venkatesha Prasad, et al., “Comparison of voice activity detection

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[2] K. Maheswari and M. Punithavalli, “Receiver based packet loss

replacement technique for high quality VoIP streams,” in Nature &

Biologically Inspired Computing, 2009. NaBIC 2009. World Congress

on, 2009, pp. 1669-1672.

[3] B. Milner and S. Semnani, “Robust speech recognition over IP

networks,” in Acoustics, Speech, and Signal Processing, 2000.

ICASSP '00. Proceedings. 2000 IEEE International Conference on,

2000, pp. 1791-1794 vol.3.

[4] P. Pragtong, T. J. Erke, and K. M. Ahmed, “Analysis and Modeling of

VoIP Conversation Traffic in the Real Network,” in Information,

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[5] L. Yuanchao and Z. Ye, “Correlation-Based Traffic Analysis on

Encrypted VoIP Traffic,” in Networks Security Wireless

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[6] C. Hui Min and H. S. Matthews, “Comparative analysis of traditional

telephone and voice-over-Internet protocol (VoIP) systems,” in

Electronics and the Environment, 2004. Conference Record. 2004

IEEE International Symposium on, 2004, pp. 106-111.

[7] M. Jaiswal and B. Raghav, "Cost-quality based consumer perception

analysis of voice over Internet protocol (VoIP) in India," Internet

Research, vol. 14, pp. 95-102, 2004.

[8] P. Setthawong, V. Vannija, M. S. Siam Yamsaengsung, and B.

Patasratorn, "An Overview of VoIP for End Users in Thailand,

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[9] T. Ulseth and F. Stafsnes, "VoIP speech quality-Better than PSTN?,"

TELEKTRONIKK, vol. 102, p. 119, 2006.

Number of Participants

0

100

200

300

400

500

600

700

Nationality Faculty Degree Gender Age

Attributes of Participants

Fig. 2. Histogram of student’s attribute

Nationality Asia Continent

Local (Malaysian)

Other Continent

Faculty Engineering

Non-Engineering

Degree Undergraduate

Postgraduate

Gender Female

Male

Age <= 25

>25

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