Telephony Applications for Handheld Computers

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Telephony Applications for Handheld Computers

• Keith Weiner
• DiamondWare

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VoIP on PDAs

• What is it?
• What is it not?
• First, why telephony on any computer??
• Then why on a PDA?
• What does it take?
• Not a (near term) replacement for cellular

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Voice over Internet Protocol

• Using private network, or public Internet
• Sending voice packets
• Endpoints are IP phones
• Switches allow legacy handsets
• Gateways support PBXs and PSTN

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Choice of form factors
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IP Telephony on PDAs

• PDA is a real computer
• 802.11b is a broadband wireless network
• Add external headphones
• Use the built-in microphone
• Shame on Compaq, HP, AudioVox, etc.
• Everything necessary for a phone

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What is it not?

• Its not cellular
• Doesnt work if driving at 55 (or 95mph)
• Probably never in low-density areas
• Wont cost 0.26 per minute
• So what?
• Still valuable
• Ideal solution not available today

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Plain ol frustration

• Plain ol 8kHz audio is terrible, too

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Computers change everything

• Presence
• Availability
• Under user control
• one address to call
• portable worldwide
• e.g. SIPkeith_at_dw.com

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Computers also add features

• Record important calls
• Multimedia calls
• text (IM)
• graphics and files
• whiteboard (doodle on PDA)
• Audio processing effects
• conferencing team tagging, 3D localization
• voice disguise

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IP is cooler than PSTN

• N-way (why just 3-way) calling?
• No need to pay for voice mail
• IP lines are never busy
• Automatic follow-me logic
• IP (data) is billed by the month
• PSTN (voice) is billed by the minute

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PDA for voice!

• How many devices do you want to carry?

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PDA for voice!

• PDA will be mission-critical
• You will carry it for many reasons
• Why not use it for the voice function?
• No worse off than before
• Within wireless zones, much better

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Cellular is poor

• Audio quality matters
• near toll quality means lower quality
• Latency matters
• Try cell to cell, with different carriers
• 1.2 second delay Hello, over?
• ellllovver on remote phone
• transcoding

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But everyone uses cellular

• On the road
• At lunch
• In coworkers offices
• Out of habit, even at their own desks!
• Mgmt. losing control and predictability
• voice minutes negotiated in bulk

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What does mobile VoIP take?

• A real CPU
• 10 to 20 of 206MHz StrongArm
• add 10 to 20 more for processing like echo
• Not on current Palms or Blackberries
• OS is not so critical
• Windows CE PocketPC
• Linux Sharp Zaurus

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What must happen next?

• Ubiquitous Wireless access points
• inside enterprise is easy
• not yet
• answers on the business side
• free, to get people to drink Starbucks coffee?
• by the minute at airports?
• 1000 minutes/month like cellular?
• by the day at hotels?

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Progress Today

• Trade shows offer 802.11 to attendees
• 40 of enterprises have wireless nets1
• 1K 802.11 US public APs in 20012
• 4K predicted by end of 20023
• Airport and hotel markets being pursued
• Starbucks

1Microsoft survey 180 companies with 500
PCs 2Gartner study, March 15 2002 3Kevin Werbach
of Release 1.0
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Challenges Today

• NATs, Firewalls, and Proxies
• PSTN Gateways not ubiquitous
• 802.11b susceptible to interference
• 802.11a promises to be significantly better
• On the road means cellular

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About me

• CEO of DiamondWare
• Developers of low-latency voice software
• mailtokeith_at_dw.com
• cell [phone]
• SIPkeith_at_dw.com (coming soon)