VoIP in Tandem with Traditional Phones

As it has been stated earlier, phone and cell phones all over the world are using circuit switching to connect calls with other phones.

But VoIP is a packet switch based technology, so your phone call must go through something (technology) that will convert your traditional phone calls into Internet protocol (IP) packets for transmission over the internet.

This technology can either be included into the phone itself ex.VoIP Phones or IP phones or in a separate box like an ATA (Analog telephone adaptor).

IP phones have all the necessary hardware and software embedded in it to convert your speech for packet switching.

On the other hand, the ATA allows you to connect a standard phone with it and from it to your computer in order to convert the analog signal from your traditional phone into digital data for transmission on your computer.

After the call is transmitted over your computer it needs to be converted from digital data to packet data. Software installed on your computer (e. x. Skype) does that conversion. When you call someone, the software chops down your voice into several packets and wraps those packets with following information:-

• What kind of data is in the packet, e. x. is it voice, text or video
• How it fits with other data or the sequence of data,
• Where the data came form, ex. Your phone number or Caller ID
• Where is the final destination, e x. Your dialed phone number

This packet switching is same like postal letter (packet), we wrap the letter in an envelope and on the envelope we write the receiving persons address and our address.

All these packets then travel across the internet network. Different packets from the same phone call don’t have to follow the same path or dedicated connection like PSTN does.

If one path becomes clogged with traffic in global internet network, then a packet can go through another pathway. That’s the part what makes VoIP so robust and fast.

As all the packets arrive, the receiving computer reassembles the data packets like puzzle and routed the call to a local circuit switch or traditional phones. The whole process happens just in milliseconds, so the caller and called person can speak in almost real time.

Now, there is an in-between important player or mediator in VoIP. After voice packet data transmitted over the internet, it need to be recognized where to send the data. Without knowing where to send the data, your call can end up to a wrong number. In VoIP, this valuable task is performed by soft switches. You can have a look on the article “what is soft switch” (hyperlink it) to get more clear idea of soft switch.