The service uses a router that accepts SIM cards for authentication, but the backhaul is pure VoIP over Internet. Regular POTS (plain old telephone service) phones can be plugged into the router. The router is also compatible with HotSpot@Home (an additional $10/month), which allows unlimited domestic calling over Wi-Fi using special handsets from T-Mobile; there are now 8 handset models available. Customers have to have at least a $40 single-line or $50 family plan service to add either @Home or HotSpot@Home.

Probably the key remaining advantage for Vonage and other Internet telephony services that typically charge $20 to $30 per month for unlimited calling is that they include unlimited calls to any number in Canada or the U.S., not just the U.S., as well as unmetered calls to landlines in dozens of other countries in Europe as well as Australia. For those who regularly call outside the U.S., the @Home service would quickly become ridiculously expensive for its international tolls.

The new compression technique, called variable bitrate compression produces different size packets of data for different sounds.

That happens because the sampling rate is kept high for long complex sounds like "ow", but cut down for simple consonants like "c". This variable method saves on bandwidth, while maintaining sound quality.

VoIP streams are encrypted to prevent eavesdropping. However, a team from John Hopkins University in Baltimore, Maryland, US, has shown that simply measuring the size of packets without decoding them can identify whole words and phrases with a high rate of accuracy.

The technique isn't good enough to decode entire conversations, but it's pretty impressive.

O2 will offer iPhone 3G for free along with extensive Wi-Fi coverage: AT&T may still be sorting out how Wi-Fi service will be included in its cell plans, but O2 had already provided free Wi-Fi to supplement scanty EDGE service in the UK. The new iPhone 3G will be offered fully subsidized to subscribers of £45 or higher tariffed services, along with 9,500 hotspots through BT OpenZone and The Cloud.

SanDisk buys MusicGremlin: The innovative Wi-Fi-enabled music player was and remains far in advance of the features found in the iPod touch, iPhone, and Zune, but the company behind the product couldn't get a fire lit under it. Sales figures were never disclosed, but it's never been on the list of top-selling players in the market. SanDisk's acquisition will shut down the product and its music service, but it will absorb the people and technology. I met with the founders of the company many years ago, and were impressed by how far ahead they were of everyone in the industry.

Zyxel introduces VOIP-connected Wi-Fi camera: I think they threw a bunch of buzzwords into a blender, but it's rather clever. The camera connects to a network via Wi-Fi, and has SIP (Session Initiation Protocol) embedded. SIP is used for VoIP and as part of gatewaying Internet telephony. The V750W gets its own phone number, and can be controlled remotely through either a real phone using the public telephone network, or a soft phone using SIP. It's being resold, not sold to consumers directly, as a monitoring tool. It includes two-way audio. The camera can also place a phone call if an intruder monitor is tripped. Why not just give it an IP address like other such cameras? SIP, if implemented correctly, can traverse private networks' NAT (Network Address Translation) gateway limits.