1. VoIP on the iPhone: Imagine the Possibilities Jan Linden, VP of Engineering

2. VoIP on the iPhone Outline Market trends Technology trends Mobile VoIP challenges Solutions and recommendations

3. Evolution of IP Voice and Video Processing Solutions Designed Specifically for VoIP Advanced Mobile and Multimedia Capabilities PSTN Solutions Adapted for VoIP

4. Mobile Market Trends Fixed Mobile Convergence –Mobile phone increasingly perceived as a computer Advanced operating systems such as Apple OSX are making this a reality –Users expect to access the same applications available across multiple platforms Increased accessibility and affordability –Network operators are introducing new pricing models to encourage uptake of data driven services and applications IP networks enable more cost effective transport –Handset prices declining iPhone 3G half the price of 1 st Generation

5. Mobile Technology Trends Migration from legacy cellular to next-gen networks –Allows for faster data connection Growth of Smartphone adoption –iPhone and other dual-mode phones provide greater flexibility in connecting to available networks –All-in-one devices able to run multiple applications efficiently Consumers can place calls and receive data simultaneously Development of 3 rd Party Applications –Operating systems, like the Apple OS X, more conducive to advanced 3 rd party applications –VoIP over mobile in high demand

6. The iPhone as a VoIP Platform iPhone most VoIP friendly phone on market… – Open APIs for easy development – Sufficient CPU resources – Support of wideband codecs – Intuitive UI makes for simple navigation between applications – Demand for 3 rd party apps is higher than other phones …but strengths present unique challenges – Running too many applications can drain resources – Usage scenarios can negatively impact voice quality With the right voice processing software, developing VoIP applications is a cinch!

7. Technology Challenges – Network Connections IP Networks –Latency –Jitter –Packet loss Wireless connections –Low signal strength –Interference from users in same or neighboring frequencies –Available bandwidth varies –WiFi access point bottlenecks

8. Technology Challenges Device Limitations –Limited processing power –Battery life –Data intensive applications can cause jitter Mobile Environments –Tend to have excessive background noise –Hands Free operation enhances acoustic echo

9. Impact of IP Networks Delay Packet Loss Network Jitter

10. Impact of IP Networks – Latency Major effect is “stepping on each other’s talk” Usage scenario affects annoyance factor – higher delay can be tolerated for mobile devices Long delays make echo more annoying 101110001011011111010 001100111

11. Sources of Latency Codec Capture Playout Network delay Jitter buffer OS interaction Transcoding A/D Pre- processin g Speech encoding IP interface D/A Post- processin g Speech decoding Jitter buffer IP Network A/D Pre- Processing Pre- Processing Speech Encoding Speech Encoding IP Interface D/A Post- Processing Post- Processing Speech Decoding Speech Decoding Jitter Butter Jitter Butter IP Network

12. Impact of Latency on Voice Quality ITU-T (G.114) recommends: –Less than 150 ms one-way delay for most applications (up to 400 ms acceptable in special cases) Users have become accustomed to longer delays –Still, low delay very important for high quality Data from ITU-T G.114 1 2 3 4 0250500750 One-way transmission time [ms] Mean Opinion Score

13. Impact of IP Networks – Packet Loss and Jitter Packet Loss – Occurs due to flushed buffers in network nodes – Same effect if packets are too late to be used – Smooth concealment necessary Network Jitter – Transmission time differs for each packet – Jitter buffer necessary to ensure continuous playout – Trade-off between delay and quality

14. Technology Challenges – Mobile Environments Background Noise –Environments inherently noisy –Usage scenarios can make differentiating between speech and noise difficult Acoustic Echo –Speakerphone operation common for iPhones –Micropohone and speaker close –High delay in VoIP makes echo more prominent

15. Technology Challenges – Devices Limited Resources –Size limits processing power –Battery life also limited VoIP Friendliness –Many smartphones limit access to soundcard –Device buffers add latency –Clock drift Too much of a Good Thing –Running too many applications can drain resources –Multiple applications accessing network can result in jitter

16. VoIP Design Considerations Quality Cost Speech Quality Time to Market Flexibility Ease of Use Network Impairments Power Consumption Device Considerations Cost Signaling Features Infrastructure

17. Coping with Network Degredation Power Consumption Hardware Issues (Processor, OS, Acoustics, etc.) Echo Cancellation Additional Voice Processing Components Environment – Background Noise, Room Acoustics, etc. Speech Codec VoIP Design Challenges Network Codec Hardware Echo Power Voice Environment Mobile VoIP Design Considerations

18. Speech Codec Packet-loss Robustness Memory Sampling Rate Complexity Delay Bit-rate Quality Complexity Bit-rate Many conflicting parameters affect choice of codec Determines upper limit of quality Support of several codecs necessary –Interoperability –Usage scenario IPR issues a significant concern Input Signal Robutness

19. Audio Bandwidth Effect on Quality Better than PSTN quality is achievable in VoIP – Utilizing full 0 – 4 kHz band in narrowband – Wideband coding offers more natural and crispier voice Frequency 4 kHz6.4-7.0 kHz GIPS Narrowband Speech Std Wideband Speech (e.g. G.722.2) CD -Audio Std Narrowband Speech Implementation (PSTN) 200 - 3400 Hz GIPS Wideband Speech 3,422.1 kHz 8 kHz Quality

20. iPhone Specific Challenges Applications cannot run in the background Audio HAL APIs (regular APIs) not available on iPhone. (As on Mac.) Very iPhone specific solution had to be designed Must consider change of audio route (e.g. headset in/out) and handle this Wideband audio not available via built-in mic

21. Recommendations IP Networks –No need for dedicated bandwidth if solution includes high performance: Bandwidth management Robust codec framework –Low latency achieved by efficient jitter buffer Audio –High quality audio is crucial Users expect the same quality they experience on the PC Optimized Solutions –Efficiency for ARM processors on iPhones –Reduce CPU constraint and increase battery life

22. Recommendations Adaptive Jitter Buffer and PLC –Manage up to 30% packet loss –Adapt to network busts and excessive mobile jitter Codecs Designed for IP Networks –Work in tandem with jitter buffer to overcome packet loss –Can deliver Wideband experience –Robust and bit-rate adaptive codecs necessary Efficient use of the total available bandwidth GIPS iLBC already in the iPhone, GIPS iSAC and other wideband codecs provide even better user experience Aggressive Voice Quality Enhancement –Detect and cancel background noise –Suppress acoustic echo

23. Recommendations VoiceEngine Mobile for iPhone –Comprehensive package of voice processing components –Handles delay, jitter, packet loss and mobile environments –Optimized for iPhone and Smartphones –Efficient solution reduces CPU demands –Flexible and easy to integrate