oFono - Open Source Telephony
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Copyright (C) 2008-2010  Intel Corporation. All rights reserved.


Mission statement
=================

The overall goal of the oFono project is to create a telephony host stack
for embedded/mobile and desktop systems based on Linux.

It currently targets GSM/UMTS User Equipment (UE) based on 3GPP standards,
but is of course not limited to that. Extensions for other telephony systems
like CDMA/EVDO are more than welcome.

Within oFono there is clear abstraction between the application interfaces
based on D-Bus, the hardware level (via drivers) and the integration with
other system components (plugins). The whole architecture is modular and
flexible.


Telephony features
==================

The oFono stack will support the majority of the features from the 3GPP
specification, but not all of them. The whole standard is pretty complex
and some features are not used in any mobile network so far, some of them
are outdated and have no relevance anymore. This paragraph tries to give
some insights on what has been implemented so far, what is coming in the
future and especially what will not be part of oFono.

Current implemented features:

	Modem abstraction

		Currently there are two modem drivers available.

		The "atmodem" driver handles hardware based on the 3GPP
		TS 27.007 standard.

		The "isimodem" driver handles Nokia based PhoNet modems.

	Network registration

		The network registration interface contains support for
		network detection. It also handles the automatic or manual
		registration to a mobile network.

		Additional information about the current network can be
		easily retrieved and displayed to the user.

	Voice call handling

		The voice call interface handles simple call creation and
		termination. It also supports 3way-calling and multi-party
		features.

		This is only for voice control. It doesn't contain support
		for the voice data path/routing.

	Advanced voice call control

		Features like COLR/CLIR/CLIP/COLP are supported by the
		voice call handling interface. 

		The support for call forwarding and call waiting is also
		present.

		Interfaces for call barring and advice of charge do exist,
		but highly depend on if the operator supports them.

	Call history

		The call history is realized via a plugin interface and
		not handled directly. This allows an easy integration with
		storage systems like Evolution-Data-Server.

	Phonebook support

		The storage of the SIM card is not used. The only supported
		feature is to export the contacts stored on the SIM card to
		some third-part entity.

		SIM card storage is limited, slow and not flexible enough
		for modem telephony applications.

	Short message service

		The SMS support for text messages is available.  oFono
		supports concatenated messages of up to 255 segments, UCS2 and
		GSM alphabets as well as extended alphabets.  SMS status
		report features are not yet available.
		
	SIM PIN handling

		SIM PIN locks, network and service provider locks are
		supported.

	Cell Broadcast

		Cell broadcasts should be fully supported by oFono, but have
		not been well tested.  Base station name ids have been
		confirmed to work.

	GPRS

		GPRS data connections are fully supported by oFono.  However
		this support is currently limited to just one active GPRS
		context (network interface).

Work in progress features:

	USSD

		User initiated USSD support is available, but not
		network-initiated USSD support.

	PPP

		Modems that use PPP for data connections are currently not
		supported.  This feature will be available once a functional
		userspace ppp stack is available.

Not implemented features:

	SIM card storage

		The SIM card storage will not be used by oFono. It is slow,
		limited in size and flexibility. It is an outdated interface
		that makes no sense in a modern telephony system.

		Export of stored contacts from the SIM card is supported for
		legacy reasons and to allow a smooth transition.

	WAP support

		The WAP feature is outdated and using full Internet access
		with an embedded browser is the future.

	MMS support

		The MMS support should not be part of oFono itself. The best
		idea is to implement a MMS service that runs in the user
		session and uses oFono's SMS interface to listen for
		notifications.

		Similar to the split between BlueZ and OBEX daemon.

		Especially when it comes to image conversion and other tasks
		that MMS support requires it is important to NOT do this as
		a system daemon.

	EMS support

		This is an Ericsson specific standard and not widely spread
		across the handset manufactures.

	Video telephony

		Currently there are no plans to support this. The support
		from the networks and available handsets are still limited.

		This needs re-evaluation once such a service becomes more
		prominent.

		A similar split like with MMS might be a good idea.