SOVoIP in Nutshell: 

Voice over Internet Protocol (VoIP) has changed the way people communicate by enabling telephony services on the Internet. The main technical difference between conventional telephony and VoIP is that it uses a packet switched network, the Internet, compared to traditional telephony’s circuit switched network. The introduction of VoIP has resulted in a number of VoIP specific protocols that are not interoperable and are not compatible with existing Internet protocols. Client development process for these solutions is harder as developers have to implement specific protocol stacks at the client end. Changes in these architectures require upgrading all the clients which involves significant work and cost.

VoIP expands not only across geographical boundaries but also over varieties of hardware and software platforms. Providers/users all over the world may not use the same platform. Moreover, users may need to stick to their deployed protocols for specific business reasons but are still required to have interoperability with the external world and with other existing systems. Web services provide a solution to these problems.

In this paper we propose a web service based peer to peer architecture for VoIP, Service Oriented VoIP (SOVoIP). Our architecture provides interoperability between protocols both from telephony and data networks using the converging behavior of web service, while ensuring security, extendibility and mobility. We also address other critical issues related to VoIP such as NAT and firewall traversal, Enhanced 911 (E911) and Communication Assistance for Law Enforcement Act (CALEA). SOVoIP also provides modularity and reusability, making the client development easier. Extendibility in the web service architecture is transparent to the client. Thus, frequent client updates are not required in order to consume new features. It saves significant upgrade cost and time.

Skype is one of the most popular VoIP architecture. Skype has heavy clients that form a peer-to-peer network. Skype uses a proprietary protocol and its messaging is encrypted. It uses TCP for call setup. Similar to Skype, H.323 an umbrella recommendation for VoIP from International Telecommunication Unidon (ITU) uses TCP for call setup. Its binary encoding and requirement for extra configuration in the network makes it complex. Compared to H.323, SIP from Internet Engineering Task Force (IETF) is lightweight and simple. It demands network configuration in each domain. SIP’s text based messaging makes the development easier. It works both on UDP and TCP. Both H.323 and SIP uses Real Time Transport Protocol (RTP) for media communication. The above mentioned protocols are not interoperable with each other and with other existing Internet protocols. Other studies tried to introduce middleware in order to solve above mentioned problems, lack some important functionalities for VoIP such as user’s physical location tracking in emergency.

SOVoIP has the added advantage of simplicity, modularity, extendibility, interoperability, NAT and firewall traversal. SOVoIP’s call setup and authentication is simple and it addresses the 911 emergency issue. As opposed to all currently available VoIP protocols those merely introduced new protocols for voice over the Internet, SOVoIP proposes a unified platform via web services. Different protocols from telephony and Internet can join SOVoIP, yet retain their protocol specific behavior as usual.

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