Truphone is a mobile VoIP/internet telephony operator. It provides Symbian software and a network infrastructure that allows people to make telephone calls and send SMS text messages over the internet from WiFi-enabled Nokia Series 60 smartphones. A version for the Apple iPhone and iPod Touch was also released in July 2008. Calls and SMS texts to other online Truphone users are free, and calls or texts to other numbers are chargeable.

Truphone uses the Session Initiation Protocol (SIP) open standard, which competes with other VoIP standards such as UMA and proprietary protocols such as the Skype protocol.

Truphone (a trading name of Software Cellular Network Ltd) was founded by James Tagg and Alistair Campbell. It has received three rounds of private investment since 2006, from investors including Alexander Straub, Eden Ventures, Wellington Partners Venture Capital, Independent News and Media, and Burda Digital Ventures.

In April 2008, Truphone acquired the business of Sim4Travel, including a GSM core network, as part of its stated strategy of offering "global mobile operator services".

Truphone's headquarters are in London, UK.

Purpose

As with most mobile VoIP applications and services, Truphone is used by people either to save money on phone calls and SMS messages (especially to international destinations), or to compensate for poor in-building cellular coverage.

Features

The essential functionality of Truphone is to provide internet telephony on mobile handsets: mobile VoIP. Calls are typically made entirely over Wi-Fi and the Internet, bypassing the traditional GSM network operators.

The Truphone Series 60 application is the most mature and allows the user to do the following:

• Make outbound VoIP calls to any PSTN number (except for certain premium rate numbers). It is possible to make calls using either WiFi or a 3G cellular data connection. WiFi is generally preferred because of the deleterious effects of continuous 3G data usage on battery life, and because of the potential costs.Fact: date=October 2008
• Receive inbound VoIP calls. Users in the UK and USA are allocated a "Truphone number" that can be called from the PSTN. Users in other countries display their cellular number as the Caller ID when making outbound VoIP calls, and can only receive inbound VoIP calls from other Truphone users.
• Send and receive SMS text messages over IP.
• Make automated call-through calls. Branded as Truphone Anywhere, this, by default, redirects international calls to a local access number and completes the rest of the call over the internet. This is intended to be used when WiFi is not available, by users who have a bundle of national calling minutes included as part of a monthly cellular contract, but pay high per-minute charges for international calls.
• Make automated call-back calls. This is intended for use when roaming abroad out of range of WiFi because inbound calls are often substantially cheaper than outbound calls. It is turned off by default because the circumstances when this saves money vary from country to country and depend on the user's cellular tariff.