• Launchpad Entry: arm-m-telephony-stack

  • Created: May 5, 2010

  • Contributors: David Sugar, Alexander Sack

  • Packages affected: ofono, telepathy, telepathy-ring (NEW), empathy (dialer)


This spec explores how to integrate the oFono middleware in the existing telephony stacks, how the telephony stack can be improved in general and how we can unify the software, application development and user experience of both telephony and VoIP. In particular this spec intends to address the steps we can take in Maverick to further this goal.

This spec proposes integrating oFono with telepathy by integrating the telepathy-ring package shipped by Meego:

This spec proposes adding a PoC dialer UI that automatically selects sip vs. oFono calls or lets user choose which stack to use for the call.

This spec proposes to integrate the dialer application with the address book infrastructure of evolution-data-server and akonadi based distribution profiles.


Getting a fully integrated telephony stack in place serves a few purposes. The most significant ones are:

  • enable vendors and hardware manufacturers to easily showcase and test their hardware using a standardized telephony stack for Linux.
  • standardize the telephony stack and encourage vendors to contribute to a single project that would open doors to all Linux devices.
  • enable downstreams and distributions to efficiently create phone and handset solutions without having to do considerable development and integration work.


A USB modem can be acquired that has free drivers in the mainline kernel and is supported by oFono (or alternatively can be enabled in oFono with reasonable effort) (Action: Pete Goodall)


We pair oFono with telepathy. A glue for pairing oFono and telepathy has been made available by the meego project and is called telepathy-ring, whose git branch is available at the URL below:

We add a dialer application that allows to showcase and test the telephony and hardware stack in telepathy enabled distribution profiles

Reaching out to empathy developers to develop this dialer application in the empathy framework is considered important and recommended as it was mentioned during UDS that they plan on working on such dialer UI anyway.

On top we integrate the telephony dialer in common addressbook services:

  • evolution-data-server
  • akonadi

Integration is targeted to happen by using a protocol scheme.


Fulfill Assumptions:

  • find and get access to USB modems that can do voice calls (GSM + CDMA)
    • ensure that free drivers exist
    • ensure that an oFono backend can be made available

Core Stack work:

  • make an oFono build available that supports the modem selected above
  • ensure that oFono in the archive is modern enough for telepathy-ring
  • identify other minimum package requirements for telepathy-ring (dependencies, minimum versions, etc.) and make a plan to fulfill those requirements in the archive
  • coordinate with stakeholders of the software stack components touched for this specification
  • ensure that minimum package requirements are fulfilled; this involves updating packages required for telepathy-ring
  • package and stabilize telepathy-ring

UI stack work:

  • initiate discussion with empathy developers on what can be achieved this cycle
  • integrate dialer application from empathy
  • or develop a simple dialer on our own
  • package and make dialer available in the archive
  • setup protocol schemes and hook that up to the dialer.

Release Note

Linaro Core comes with an extended telephony stack built on telepathy; the middleware stack is included in the headless and netbook distribution profiles; a showcase dialer UI is available in the the netbook distribution profile.

UI Changes

For netbook and phone profiles, integrate latest empathy and ensure that there is a separate dialer application suitable for touchphones.

Test/Demo Plan

Unresolved issues

UDS Maverick Discussion

Problem Space

  • Lots of communication methods and services
    • with different api's
    • different client experiences
    • ranging from VoIP to cellular, and all in between
  • Many kinds of applications
    • generic communication programs
    • specialized custom enterprise apps
    • ACD agents and relationship management
  • Need to integrate other system resources such as address books
  • Telephony application development often need to deal with audio processing
    • and different network transport protocols long before the "application"

Proposed Goals

  • Unify disparate communication systems with different api's
  • Simplify telephony application programming
  • Single solution that works for cell phones to desktop


  • Is desktop agnostic essential?
  • Can we use just a heavyweight client with an external API?
  • Does a heavyweight client effect agnostic and lightweight environments?
  • Can we use ofono as a top layer telephony application stack?
  • How much work is needed to make ofono usable this way in Ubuntu?
  • Can we reduce telephony application development to something like "quickly"?
  • How have others tried to solve this, and what can we learn?

Discussion Notes

  • What are the differences and advantages of Ofono regarding Telepathy?
    • Telepathy has a more complete/complex API, aka ofono would restrict the feature set
    • oFono plugin for telepathy exists for nokia, but is currently closed source
    • call routing: might not work on phones; power consumption for VOIP isnt optimal
      • preferred way to route calls could be auto selected; where? client needs to take care
        • because telepathy has no concept to do that; client could be != UI
    • priority should be to get use cases and devices work; then think about UI
    • integration with bearer management to make call routing decisions

Action Items

  • bearer management service as part of the default
  • client that integrates with bearer management, address book (eds, akonadi), telepathy
  • sipwitch as proxy service? benefit: smart voip routing, smart NAT support, multi-device handling
    • 100k overhead
  • package ofono and friends
  • UI: DTMF dialer; bearer management problem; should we extend the empathy UI?
  • complicated question: how to do routing? where do do that?

Telepathy contacts: sjoerd rob mcquen


Specs/M/ARMTelephonyStack (last edited 2010-06-07 14:34:31 by afrantzis)