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Mobile VoIP - TKK - TML

Mobile VoIP - TKK - TML






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    Mobile VoIP - TKK - TML Mobile VoIP - TKK - TML Document Transcript

    • Internet telephony going mobile? Anders Rotkirch, 50348V Research Seminar on Telecommunications Business II T-109.551, Spring 2005 anders@rotkirch.com Abstract interesting ways of how VoIP can be used in the short term from a mobile terminal, but not necessarily a As Internet telephony is becoming more and more mobile VoIP terminal. popular in fixed networks, the interest of Internet telephony in mobile networks arises. Depending on the wireless access technology, whether it is a TCP/IP connection or not and depending on the There are many ways how we can use Internet connection speed, there are different ways or scenarios telephony or VoIP (Voice over IP). This essay will of using VoIP. begin with some concepts associated with information technology goods. Then a short overlook at the This paper studies how VoIP can be used in mobile protocols associated with VoIP and with wireless networks, both existing and new. Some networks communication is presented. By looking at how mobile provide greater mobility and some greater speed. Some VoIP can be used, three use case scenarios are offer direct TCP/IP access, some do not. Making the introduced. At the end of this paper the advantages and integration seamless is therefore an important point. disadvantages of each scenario will be presented. This paper emphasizes on how we use mobile Internet 2. Success Factors in the New Economy telephony today and how we will use it in the future, not on the in-depth technology or on specific business In the book Information Rules, Carl Shapiro and Hal R. cases. Varian write about durable economic principles that hold in the New Economy. As always there is a market uncertainty involved when new services become Key Words available. Even though new technologies constantly arrive the principles remain. Mobile VoIP, VoWLAN, VoWiMAX Creating a solution that binds the customer to that solution is called lock-in effect. The lock-in effect is the 1. Introduction result of the costs that a user has to pay for switching to a competitor. Knowing how to take advantage of this Although VoIP is a relatively old technology it has effect is a huge competitive advantage. The lock-in become somewhat of a hype today. Already in 1995 effect is usually easier for the first movers since they there was a free VoIP software client called PGPfone. enter the market first. (Shapiro and Varian 1999, p.11) (Internet Calls (VoIP) 2005). The positive feedback that arises from a service is when Flat-rate broadband Internet access and solving some the addition to the network benefits the whole network. technical problems with firewalls are the two most The classical example is the fax machine. If no one has important factors for the VoIP gaining in popularity. a fax machine, having one is pointless. On the other (Company 2; Company3) hand as more fax machines there are the more useful they become. Compatibility issues are important here. It The thought of free calls is an excellent selling is of course harder to start a new market than to evolve argument which also explains the current hype. The best from a previous one. The dominant model is the set of known VoIP client today is probably Skype. Skype has product and or service that has become the market today over 35 million active users and is gaining leader. Being compatible with the current dominant 150,000 new users each day. (Skype 2005) model is always an advantage. (Shapiro and Varian 1999, p.13) Of course the calls are not totally free, but in the best case the end user only has to pay for the Internet access The basic pricing strategy is usually either to cover the network costs. The convergence of differentiation or cost leadership. Differentiation means different types of media towards an all IP future has adding value to the product or service to be clearly begun. distinguished from the competition. Cost leadership is making the product or service cheaper than the In mobile networks this convergence is taking a longer competitors by the means of economies of scale and time. Even though in the end all voice communication scope. (Shapiro and Varian 1999, p.25) might be VoIP, mobile or not, there are many
    • 3. What is Mobile Internet Telephony? company that has successfully integrated Mobile IP and IPSec. (Secgo 2005) 3.1 What is VoIP? Motorola, Avays and Proxim's solution for WLAN and cellular convergence is called Seamless Convergence. Wikipedia, the online dictionary defines Internet BridgePort Networks, IBM, Verisign and Cisco telephony as the "technology that enables routing of announced their solution MobileIGNITE in January voice conversations over the Internet". Voice over IP or 2005. (Finneran 2005) VoIP, is the name of the protocols that are used for Internet telephony. The most common VoIP protocols are RTP, SIP, H.323, H.248, MGCP, IAX, G.711, 4. Different Ways of Using Mobile VoIP G.729 and iLBC. (Wikipedia 2005) The telecoms consultancy firm Analysys proposes five RTP or Real-time Transport Protocol is a IETF different types of VoIP in a report for the European application layer protocol used to deliver audio and Commission (Analysys 2004): video packets over the Internet. (RFC 3550) Self-provided consumer: Usually free, PC-2-PC For signaling the Session Initiation Protocol (SIP) is (e.g. Microsoft Messenger and Skype) becoming more and more popular and is gradually Independent of Internet access: Usually not free, but replacing ITU's H.323 umbrella of protocols. cheaper than a normal phone subscription (e.g. Vonage and www.laajakaistapuhelin.fi) The most common speech codecs are G.711 and G.729 Provided by broadband access service provider: which are both specified by ITU-T. G.711 is used for Additional service or included in a broadband DTMF and fax tones while G.729 is used for subscription (e.g. Sonera Puhekaista and compressing voice. iLBC is a license free codec which www.free.fr) is gaining popularity fast because it handles lost packets Corporate internal use on business LAN/WAN: All- well. (Internet Calls (VoIP) 2005) IP enterprise networks. Carrier internal use: All-IP operator (e.g. Song's There are also popular proprietary protocols. Cisco for 99577) example, has Skinny Client Control Protocol but the best known today is probably Skype's peer to peer VoIP This categorization does not include a separate view on protocol and Global IP Sound's audio codec which mobility. The Finnish Ministry of Transport and Skype uses. Telecommunications has noticed this in their report and has therefore proposed another categorization into three different types. (Internet Calls (VoIP) 2005) 3.2 What is Mobile VoIP? Service at a fix location: Available only at a specific If the definition of mobile Internet telephony is location (e.g. Sonera Puhekaista) analogue with the definition of Internet telephony then Nomadic voice service: Possibility to access the mobile VoIP could be defined as the protocols that are service when there is a fast enough Internet access used for mobile Internet telephony. This means that the (e.g. Skype and www.laajakaistapuhelin.fi) end terminal needs to be mobile (to some extent) but Mobile service: Wireless TCP/IP networks (e.g. 3G not necessarily a true VoIP client. and WLAN) Mobile VoIP is thus VoIP used from a mobile terminal. As noted in both categorizations above, VoIP can be The wireless connection can be for example Bluetooth, used in a wide variety of ways. Even though the DECT, WLAN, WiMAX, GSM, GPRS, EDGE or connection might not be TCP/IP from end to end, VoIP UMTS. Notice that not all these wireless connection can still be used effectively on the way. In the following methods support TCP/IP. In these cases there has to be figure (Figure 1) three different ways of using and a VoIP gateway somewhere else in the network. accessing VoIP services from a mobile terminal are drawn. These ways or scenarios, and examples of them, TCP/IP was designed with a fix network in mind, not will be explained in more detail next. for mobile nodes. Mobile IP is one way of addressing this problem (RFC 2002). Roaming between different kind of wireless networks and making the integration seamless is still a challenge. This is an important issue since it makes new technologies compatible with older ones. Security issues are even more important in wireless networks since eavesdropping is by default easier than in fixed networks. IPSec is a generic Internet security protocol. In addition to IPSec PKI needs to be used for a system with public keys. Secgo is an example of
    • Figure 1: Accessing VoIP wirelessly 4.2 Scenario 2: Home or Small Office is the Operator/Enterprise VoIP Gateway Network One step closer to the end user is having a VoIP Wireless non-TCP/IP access gateway at home or in the office. This gateway can be for example a personal PC or a router connected to a Fixed TCP/IP Internet broadband Internet access. In this scenario the wireless Wireless non-TCP/IP access access connection is non-TCP/IP as well but the gateway is physically closer to the user. Wireless TCP/IP access Freenet in Germany proposes such a solution which is also compatible with traditional GSM. At home the user installs Freenet's HomeStation which is a router, broadband modem, VoIP client and Bluetooth access point, all in one. Then Freenet's iPhone is capable of 4.1 Scenario 1: Operator/Enterprise is the calling VoIP calls via Bluetooth when it is reach of the VoIP gateway HomeStation. (Freenet 2005) The most usual way today of using VoIP through a Another similar example is the Gigaset M34 USB mobile terminal is by accessing a traditional wireless DECT adapter which Siemens has launched. This non-TCP/IP network such as GSM. The VoIP gateway adapter enables DECT cordless phones to access the in this case is located at the operator. This means that PC's Skype client. (Siemens AG 2005) the user pays only for the first mile and possibly for the last mile as well. Additional services that are often In the first example a router is the VoIP gateway and in associated with VoIP can also be available. For instance the second example it is a PC. In both cases the wireless presence and profile data can be synchronized with the connection is free. VoIP server over GPRS. Many large enterprises have their own networks. That is 4.3 Scenario 3: Wireless End Terminal is why big firms can be compared to operators and why the VoIP Gateway the two are equivalent in this scenario. Having a wireless end terminal which has a VoIP client There are many examples of services that uses this is maybe the most interesting case. It is an all IP model. Telia in Finland, today TDC Song, has had for solution. The wireless connection can be any TCP/IP many years a VoIP service for international calls. By connection, e.g. GPRS, EDGE, UMTS, WLAN, dialing the prefix 99577 the call is routed via VoIP WiMAX or MBWA. Using VoIP over these internationally. Only the last mile in most cases is connections is called VoIP over GPRS, VoIP over converted back to a normal telephone call. (TDC Song EDGE, etc. or Voice over GPRS, voice over EDGE, etc. 2005) In both cases the abbreviation is VoGPRS, VoEDGE, etc. Company1 has a solution where a client on the mobile terminal always routes the call to the lowest cost. This GPRS is too slow for full duplex real time VoIP, but client is an application which is transparent to the user Push to talk (PTT) is a VoIP service which works over since it runs in the background. In GSM it updates its GPRS. It is a good example of a VoIP client in a normal routing tables through GPRS from Company1's mobile phone. Enterprise Communication Server. This means that when the call is cheaper to route through VoIP from the Today WLAN is probably the most available broadband home network then it is done. (Company1 2005) wireless TCP/IP network. There are a few WLAN VoIP phones on the market already from fabricants such as Telenordic recently launched a call back service in Vocera, Spectralink, Telesym and net2phone. These Norway. The idea is that the user dials a predefined toll terminals are still not very user friendly. Since WLAN free number and then hangs up. The service will then requires more energy than GSM networks for example, call back the caller who will then enter the actual the standby times in these phones are much lower. Also number to call. The procedure is made easier in few of them are compatible with 2G cellular networks. smartphones by installing a software that integrates with the telephone's contact lists. (Telenordic 2005). One upcoming wireless technology that makes the news regularly is WiMAX. The promises are many: large Even DECT phones can have a direct connection to a operating area, thousands of users per access point, company's VoIP enabled PBX. Then the wireless handover & roaming capabilities, 268mbps speeds both connection is DECT and the operator is the company. ways,... (O'Shea, Dan 2004) 3G networks, such as UMTS, are also suitable for VoIP. These networks support TCP/IP natively and have
    • connection speeds that are fast enough for full duplex Since users expect VoIP to be free, or at least real time VoIP. There is however a lack of VoIP substantially cheaper, the market is going to be very software clients for 3G smartphones. The pricing in competitive. The need for differentiation is growing. most countries makes it also hard to motivate the use of This can mainly be done through added value services VoIP over UMTS. to the VoIP service. These services can be ENUM compability, presence and profile synchronization, roaming, seamless integration with other networks, etc. 5. How do these Scenarios Compare? In the table below is an overview of the differences The dominant design today for wireless communication between the three scenarios. is clearly the mobile cellular phone. With a 3-band GSM phone it is possible to roam almost everywhere in Table 1: Advantages and Disadvantages the world. The phones themselves are advanced with long standby times and advanced functionalities. Feature Scenario 1: Scenario 2: Scenario 3: Operator is Home is End All three scenarios described in the previous chapter are the VoIP the VoIP Terminal is both compatible and complementary and in many cases Gateway Gateway the VoIP the products as well. Being compatible with the Gateway dominant design is a key issue. This concerns the Roaming? Excellent No Good second and the third scenarios. That is why it is possibilities possibilities important that the new products support the old network Moving Yes No GPRS, as well (e.g. as Freenet's iPhone). terminal? EDGE & 3G: yes. WLAN: no. The positive feedback network effect of VoIP is WiMAX: evident. Since VoIP to VoIP calls are generally free (at in the least within the same VoIP provider) the value of future. adding a user benefits the whole network. New end No Yes Yes Interoperability between VoIP networks is not as good terminal? as it could be. Even though most are based on the same Flat-rate No Yes Yes standards they are not always interconnected. Some possible? providers are not even interested in interconnecting with Add-on Yes Yes Yes other providers. For example Skype uses its own services? proprietary, closed standard. In mobile networks (presence, profile,...) interoperability becomes even more important since the network environment changes more frequently. In the second scenario the mobility is already very limited For scenario 3 to really lift off there seems to be a because it is set to the proximity of the VoIP gateway at parallel to VoIP in fixed networks. There seems to be a home or the office. The third scenario on the other hand, demand for a flat-priced data rate. WiMAX looks very would benefit greatly of a wide intercompatibility. promising since it addresses many of the problems with WLAN. In-Stat forecasts more than 4,4 million Having a proprietary solution, like Skype does, creates a WiMAX subscribers by 2009 (Voice over WiMAX lock-in effect. The switching costs can be higher to 2005) move to another network if it is not compatible with the old one. 3G is also a good candidate for scenario 3 since it seems that 3G in many countries is in need of a so called killer By rapidly acquiring a critical customer base the application to get subscribers. If 3G operators would advantages of being a first mover are achieved. As charge a flat-rate for the data mobile VoIP would have a noticed before, VoIP is a relatively old technology. bright future in 3G networks. Even so, companies like Vonage and Skype have become important players quite rapidly. Old Having a practically free telephone system makes telecommunications companies might fall behind. telephone spam or SPIT (Spam over Internet Telephony) a concern. In scenario 1 there is always a In all three scenarios described in chapter 4 no player small fee involved which eliminates SPIT. has succeeded as an early mover gaining a lock-in effect in mobile networks as Skype has done in fixed The substitutes to mobile VoIP must not be forgotten. networks. On the other hand, Skype was already an Normal cordless and mobile telephones are both example in scenario 2. excellent and cheap in providing voice service. Especially in comparison with scenario 3 one should The main reasons of switching to VoIP – fixed or remember the existing solution. In Finland mobile calls mobile – is cost savings. This means cost savings in are already free for big companies internally and for phone calls, cost savings in hardware and cost savings consumers the lowest price per minute is currently at in network management. (Internet Calls (VoIP) 2005) 0,069€. (Company 4)
    • 6. Conclusion m/cm/pub/showdoc.p?docid=1971&menuid=97&chann elitemid=10412 To answer the this paper's title's question, the answer is not only that Internet telephony is going mobile, but RFC 2002. IETF. www.ietf.org that it has already begun. All three scenarios already exist and will continue to expand. True wireless VoIP RFC 3550. IETF. www.ietf.org terminals that can seamlessly roam in different networks are still in the future. Secgo. 2005. Mobile IP products webpage. http://www.secgo.com/products/secgo_mobile_ip.html Flat-rate pricing and broadband wireless networks seem to be the enablers for true end to end mobile VoIP. Shapiro, Carl and Varian, Hal. R. 1999. Information Meanwhile there are many ways of how the advantages Rules : a Strategic Guide to the Network Economy. of VoIP can be used wirelessly with today's Harvard Business School Press. Boston, Massachusetts. technologies. At last, the 2G networks remain a very competitive substitute, even though that may change in Siemens AG. 2005. Gigaset M34 USB product the future. webpage. http://communications.siemens.com/cds/frontdoor/0,22 41,hq_en_0_69566_rArNrNrNrN,00.html References Skype. 2005. Press release 15.04.2005 Analysys. 2004. IP Voice and Associated Convergent http://www.skype.com/company/news/2005/skypeinsky Services. Final Report for the European Commission, pevoicemail100million.html January 2004. Voice over WiMAX: The Key to Wireless Broadband Company1. 2005. Interview with Company 1. Profitability? 2005. In-Stat Report February 2005. www.in-stat.com Company2. 2005. Interview with Company 2. Wikipedia (2005). http://en.wikipedia.org/wiki/Voip Company3. 2005. Interview with Company 3. Company4. 2005. Interview with Company 4. Finneran, Michael. 2005. The Payoff From WLAN/Cellular Integration. Business Communications Review March 2005 Vol. 35, Iss. 3; pg. 22 Freenet. 2005. Freenet iPhone information webpage: http://www.freenet.de/freenetiphone/zusatzseiten/iphon e/index.html Internet Calls (VoIP). 2005. Ministry of Transport and Telecommunications Finland Report 16/2005. http://www.lvm.fi/scripts/cgiip.exe/WService%253Dlv m/cm/pub/showdoc.p?docid=1971&menuid=97&chann elitemid=10411 O'Shea, Dan. 2004. A Standard Argument: Why WiMAX Will Rule. Telephony's Complete Guide To WiMAX 31.05.2004 http://www.wimaxforum.org/news/press_releases/Telep hony_WiMAX.pdf TDC Song. 2005. TDC Song information webpage: http://www.tdcsong.fi/index.php?path=99577_internetp uhelut Telenordic. 2005. GlobalLife home page http://www.myonephone.no/beta2/ Restraints of Communications Services. 2005. Ministry of Transport and Telecommunications Finland Report 17/2005. http://www.lvm.fi/scripts/cgiip.exe/WService%253Dlv