Free Mobile Applications

There three basic types of VoIP, one is PC to PC (or more precisely IP terminal to IP terminal), another is PC to phone or phone to PC, the last one is phone to phone. PC2PC is the initial type of VoIP. Because VoIP is based on packets routing, it is much cheaper than traditional PSTN based on circuit switching. In general, PC2PC VoIP is free and almost all popular instant messaging platforms have free VoIP integrated, for example, Skype, MSN, Yahoo!, Google Talk, ICQ and so on. And Mobile VoIP based on WiFi or 3G network also can provides such kind free service. PC2phone type became popular with the development of VoIP. In this type, the first part is PC2PC (IP terminal) and the second IP terminal is a gateway to transfer voice signal from packets routing network to circuit switching network. The main cost of VoIP is coming from the part from the VoIP gateway to the destination phone number. The VoIP calls are cheap because the signal transmission crossing continents (international) is on packets switch network and from the VoIP gateway to the destination number is only local cost. The phone2phone VoIP cames as calling cards at first. People call the local VoIP gateway first and the local VoIP gateway transmits signal over IP network to the remote VoIP. Finally the remote VoIP gateway delivers the voice signal to the destination number.

Mobile VoIP based on callback

Mobile VoIP based direct wireless data network requires handsets with powerful hardware and a lot of bandwidth. Most mobile phones are not capable for that. Callback mode are used to bypass these two difficulties. So called “callback mode” is also a phone2phone VoIP service, both parties is answering. The call center will send a request to the VoIP gateway closest to the source number, and this VoIP gateway will connect this call to the source number via PSTN network. After the source number answered, the call center will request the VoIP gateway closest to the destination number to connect this call to PSTN network. The call center will be a bridge. In the callback mode, the codec/compressing of voice signal will be performed by VoIP gateways and connections between VoIP gateways and phone number of calling parties are traditional circuit switching network, so there is no special requirement for handsets of calling parties and bandwidth. However, there is also a disadvantage, in callback mode, both side have to pay connection fee to PSTN operators.

All VoIP services have web callback option call be used on internet-enabled mobile phones, for example, Jajah, Nonoh and RakWeb as well as many products from Betamax. Except that, many mobile VoIP providers developed Java client on mobile phones to make it easy to dial via GPRS/3G network. Here are some of them

Mig33（www.mig33.com）

MINO（http://www.minowireless.com/mino/）

Tokiva（www.tokiva.com）

Vyke（www.vyke.com)

And MoTalk from Morange. In Talkonaut, You can define SIP service providers to DIY mobile VoIP.

But not all phones have internet, so some mobile VoIP provider also provide option to initial calls via SMS, for example Vyke and Morodo.

Translated from 能在手机上使用的网络电话汇总（2）

Related Post

• cellity adds worldCALL VoIP service after its free “SMS” product
• Morange adds SMS and podcast features
• Morodo VoIP offers free trial
• New Morange has MoTalk VoIP feature integrated
• How the official Skype Java mobile version works