## 2 Comparing the Telco Approach to Internet Approach
### Comparing the Telco (PSTN) and Internet Approaches  
Finally the main difference is in the dynamics of deploying new applications where usually in the telco world, it is the service provider that deploys the service, but in internet almost any person can develop his/her own applications and make them available through the internet. Generally, each service provider can deploy only a limited number of new applications each year in order to assure stability and quality, precisely test each application before deployment (e.g., that it does not affect existing applications in any unexpected way). So the service provider controls the life cycle of the introduction and phase-out of applications and services based on user demand and economics factors (revenues, economies of scale). The users in the telco world can only select from a limited number of telco services provided by service providers mainly only available in the country in which they live (therefore there is usually only limited competition in available services).  
On the other hand there is an enormous number of new applications deployed each day provided from anonymous servers around the world known only by their web addresses (which is usually also the name of the internet application provider). Some of the applications are deployed as a beta version before they achieve the required stage of quality and stability. They are repaired and improved along the way by beta trial users. Users seem to accept this and are often willing to help improve the service if they enjoy using it. We are also aware that only a relative few services provided on internet ultimately achieve user acceptance, become well-known and are used by a significant amount (millions) of users. Generally we can say that the internet works by a natural selection of services, an evolution approach known in nature that is now applied by the users themselves, who only allow survival of those applications that are really used.  
Table 1 compares the models of telco networks and internet, and highlights some main differences.  
\begin{table}
\begin{tabular}{p{142.3 pt} p{142.3 pt}} \hline \hline
**Model of connection in PSTN** & **Model of connection in internet** \\ \hline Three-way telecommunication model (calling party-network-called party) & Two-way telecommunication model (client/server or point-point) \\ \hline Standardized network telecommunication protocols, protocol transparent for all communication parties & Communication protocols, often non-standardized, agreed between the communicating parties \\ \hline QoS guaranteed by network & No support of QoS end-end \\ \hline Services provided by provider and service platform in network & Services provided on the periphery by application provider’s servers \\ \hline Billing generally used for the use of telecommunication service & Flat rate or free service \\ \hline Fully tested before deployment & Usually deployed and tested by users \\ \hline Longer lifecycle of services controlled by service provider & Shorter life cycle of service driven by user acceptance \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of originals PSTN and Internet models.