• Proceedings of the KIEE Conference
• /
• 2001.11c
• /
• pp.130-133
• /
• 2001

VoIP(voice over internet protocol) technology is based on IP protocol. The IP protocol can be involved in two types of communication: unicasting and multicasting. Unicasting is the communication between one sender and one receiver. It is one-to-one communication. Multicasting is one-to-many communication. So that, many receivers can get same data from one sender simultaneously. and, the different protocol are proposed for VoIP; H.323, SIP and MGCP. MGCP is perfect server-client protocol, so MGCP is very attractive VoIP protocol to ISP. This paper uses MGCP and offers modified MGCP for conference call. So that, Modified MGCP is compatible to MGCP, and supports conference call using IP-multicast.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.4B
• /
• pp.387-393
• /
• 2009

In this paper, we have considered the network performance of the VoIP service with the measurement by an emulator, and analyzed the major factors to affect its performance. Also, we have used the measured values to investigate the traffic variations, where their values were observed in the commercial operated network after the delay, jitter and packet loss, and loss compensation methods were applied as the dominant elements. It is expected that our presented results will be a good data to provide the high-quality of voice service in the Internet.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.8 no.6
• /
• pp.21-28
• /
• 2008

In this paper, we proposed an algorithm that reduces call setup time between the IP PBXs installed in the main office and several branch offices. In the IP PBXs installed in branch offices, we prepare some internal memory spaces, and they keep the frequently used extension numbers and the corresponding IP PBX's addresses. In order to call an extension number registered to the other remote IP PBX from an extension number registered to the local IP PBX, the local PBX searches for the destined extension from its internal memory first. If the extension is found, then the local PBX uses its corresponding IP PBX address stored along with the extension, instead of making a query to the main office's IP PBX. By this technique, we could shorten the average call setup time and verified it by an experiment.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.173-174
• /
• 2008

In this paper, we study IEEE 802.16 network for IP subnet aspects and propose optimized subnet model in accordance with IEEE 802.16 network in the point of mobility.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.10 no.6
• /
• pp.63-69
• /
• 2010

Today, Internet Telephony Services based on VoIP are gaining tremendous popularity for general user. Therefore a various demands of the user keep up increase, the most important requirements of these is voice security about telephony system. It is needed to ensure secret of voice call in a special situation. Due to the fact that many users can connect to the internet at the same time, VoIP can always be in a defenseless state by hackers. Therefore, in this paper, we have developed VPN IP-PBX for the voice security and measured conversation quality by adopting VPN IPsec based on SIP and using tunnel method in transmitting voice data to prevent eavesdrop of voice data. This VPN IP-PBX that is connected Soft-phone provide various optional services.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.5
• /
• pp.95-100
• /
• 2011

The next generation IP-PBX system are demanding multimedia facility to carry out UC(Unified Communication) and voice security also. Therefore, in this paper, we have developed the integrated solution of IP-PBX for the voice security by adopting VPN IPsec based on SIP using tunnel method in transmitting voice data to prevent eavesdrop of voice data and have shared between communication system based on PC and PSTN terminals. In particular, We have developed a video conference, private switching, distributed processing and measured telephone conversation quality. This IP-PBX that is connected Soft-phone provide various optional services.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.15 no.6
• /
• pp.89-94
• /
• 2015

FMS which has a concept that wireless terminal can replace wire terminal services is a technologies that is can provide service costs same as wire terminal in the special zone. Enterprise type of FMC that is developed making up for the weak point is must have to improve voice quality and FMC performance in the soft phone. This paper measure voice quality based on the one way of the total estimated delay time of FMC to carry out IMS services between IP-PBX and FMC soft-phone to operate it's controller optimally and put forward evidence to be in 120ms and 150ms in the VoIP FMC voice quality. To measure FMC performances in four categories evaluated trials and prove its performances.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.9 no.4
• /
• pp.115-122
• /
• 2009

These day, market demanded to a Video conference systems rapidly increases in our life for cut cost in communication. more and more it will be grow up. but the cost building to a Voice conference and a Video conference is very hight. therefore it is builded around the big company and the public office. so in this study, we have developed to hybrid IP-PBX which is able to a Voice conference and a Video conference with one system. the system developed has the merits to low-price for it's building in a small company. we make proof the performance through the test. with using the hybrid IP-PBX, we can sharply reduce to communication cost.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.10 no.2
• /
• pp.103-111
• /
• 2010

For that reason, more and more growing of the internet speed, many kind of the multimedia as if the voice, a letter, a photograph, a moving picture are appearance and integration of the internet as if the wireless internet, the CATV, a satellite is forming. Today, many changes in the communication environment are occurrence. therefore a demands of the user keep up increase. so, in this paper, we developed the SOHO IP-PBX embedded which can automatically exchange the call. the developed IP-PBX have many functions as if the exchange call function, the gateway function, the PSTN backup function, the FAX function, the VPN function, etc. and verified it by an experiment on the rules in KT.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.4
• /
• pp.83-89
• /
• 2011

Nowadays, Internet Telephony Services based on SIP are gaining an explosive increase for general user. Thus a various demands of the user about convenience of IP-PBX are growing. The most important requirements of these is hybrid IP telephony system which is connected not only internet telephone but also general PSTN telephone. Therefore, in this paper, we have developed Hybrid IP-PBX connected all type of telephony terminals for small office. We have developed FXS module for connecting all type and FXO for using PSTN telephone number also. This Hybrid IP-PBX that is can be connected Soft-phone provide various optional services. We measured voice quality and test simultaneous calling for proof of validity.