Quality of service (QoS) is a very important issue in Networking. It covers many aspects such as performance and numerous measures. It is as a result that the 2.5G, General Packet Radio Service (GPRS), which is packet-switched extension of Global System for Mobile communication (GSM) came about to meet the needs of higher bit rate and larger capacity. When GSM was first designed in 1982, no one would have predicted the growth of the internet and the rising of demand for multimedia services. GPRS boosted the GSM data services significantly by providing end-to-end packet-switched data connections. Minor changes were required in the implementation of GPRS over the already existing GSM network.Important Characteristics of 2.5G SystemEfficiency: spectrum are more efficiently used through sharing of connections among users for both data and voice communications. This facilitates the operators of wireless network to permit more users on the same network.Upgrade to 2G systems: 2.5G technologies are upgrades to existing cellular networks. The users still the same voice capabilities as the 2G but now enhanced speed data access and the same network coverage. As opposed to building new infrastructure from the scratch, mostly, moving from 2g to 2.5g involves a upgrade for the wireless carrier.Foundation of 3G infrastructure: the implementation of 2.5 technologies is the bed-rock on which the future upgrades to 3G systems is laid. From both technical standpoint and a business perspective it is true. As users experience the benefits of high-speed packet data, the will request for more capacity and speed, hereby, forcing carriers to upgrade to 3G. 2.5G provides the basic packet network on which 3G can eventually be built.Speed: 2.5G networks can provide transfer rate of data up to 115Kbps. This is a vast improvement over the 2G network. Due to the implementation of more efficient modulation algorithms and the ability to use multiple channels simultaneously for data transfer.Circuit-Switching Versus Packet-SwitchingTransfer of data is done using either of this two switching mechanisms.¬†Circuit-Switching: In circuit-switching physical connection is established between the two communicators over the networks. This established connection is kept for the duration of the connection and cannot be used by any other parties. Landline telephone networks are circuit-switched. You are granted a connection to the person you are talking to when making a telephone call. The line only becomes free and available again after you end the conversation and you drop the call. So as a result for every single call a dedicated line is needed. Circuit-switching works for voice communication where there is data constantly streaming, but not for many other forms of communications for example, browsing web pages requests communication in bursts, this is because when no data is being transferred, the connection must be maintained. This is an extra charge on the consumers’ side as they have to pay according to the time connected to the network, and not by the amount of data they have downloaded. This connection cannot be used for any other purpose thereby making it wasteful considering the wireless Operators. Lastly on this note 5-40 seconds is needed to reconnect if the connection is lost.Packet-switching: The problems enumerated in circuit-switching above are solved in packet-switching. No dedicated connections are required, instead several users are allowed to share a single connection in other to maximize spectrum. In internet traffic packet-based networks are used for data transmission. This is achieved by dividing data into smaller units. These units are referred to as packets which are given destination address that they carry around as they travel through the network. Since data packets are not following any specific path to get to their destination, multiple users can share the same data path. As a result packets take the optimal data path for the efficie