Technical Description- VoIP

VoIP stands for Voice over Internet Protocol. It is also called IP Telephony, Broadband Telephony and Voice over Broadband, Internet Telephony and Broadband Phone. It is basically the voice conversation routing over any IP-based network or Internet. Companies providing VoIP service are usually referred to as supplier and protocols, which are mainly use to send voice signals are generally referred to as VoIP or Voice over Internet Protocols. There are two PSTNs to VoIP technology. They are access numbers and DID, which stands for Direct Inward Dialing. DID connect the caller straightforwardly to the other VoIP user and access numbers are very similar to local calls. It is generally charged as a local call charge while, DID requires a monthly a monthly charge. There are some DIDs that are free of monthly charge but, require charge to call other.
For VoIP service, ITU standard H. 323 and IETF standard SIP are the two main rival standards. At first, the most prominent protocol was H. 323, though it has been exceeded by SIP in the local loop. This was because of the better traversal of firewalls and NAT, although current modifications made for H. 323 have eliminated this benefit. However, in backbone voice networks, telco or network operators control everything. A lot of huge carriers make use of H. 323 in their foundation backbones and the caller's huge majority has little or no idea that VoIP carries their POTS calls. The idea of Signaling Proxy and Full Media Proxy are important where Voice over Internet Protocol calls travel through more than one provider's softswitches. In H 323, 3 data streams make up the data; they are 1) H. 225.0 Call Signaling, 2) H. 245 and 3) Media. So, if a user is in Australia, his/ her provider is UK Broadband Company situated in United Kingdom and he/ she wants to call another user, staying in USA, then in Full Media Proxy mode, all the streams will go half way around the globe and the stoppage (maximum of 500 to 600 ms) and it will undergo a high packet loss. But, in Signaling Proxy Mode, the signaling runs across the supplier and, due to that, the hindrance is abridged to 120 to 150 ms and makes it much more user friendly. One of the major concerns with all the conventional VoIP protocols, is the packet header used wasted bandwidth. Usually, to send a G. 723.1 5.6 kbps squeezed audio pathway needs 18 kbps of bandwidth depended on standard sample speed. The dissimilarity between 18 kbps and 5.6 kbps is packet headers. A number of bandwidth optimization methods used are there, for example, header compression and silence suppression. It can usually save almost 35% on use of bandwidth. But the truly appealing technology is generated from VoIP consequences, for example, TDMoIP enjoys the advantage of bundling conversations concept, which are advancing towards the same goal and covering them up in the same packets. These can offer close to toll excellence audio in a 6-7kbps data stream. VoIP traffic is called purple minutes.

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