6303 nokia

GENERAL2G NetworkGSM 900 / 1800 / 1900Announced2008, DecemberStatusAvailable. Released 2009, MaySIZEDimensions108.8 x 46.2 x 11.7 mm, 57 ccWeight96 gDISPLAYTypeTFT, 16M colorsSize240 x 320 pixels, 2.2 inchesSOUNDAlert typesVibration; Downloadable polyphonic, MP3 ringtonesSpeakerphoneYes - 3.5 mm audio jackMEMORYPhonebook2000 entries, PhotocallCall records20 dialed, 20 received, 20 missed callsInternal17 MBCard slotmicroSD, up to 4GB, 1GB card included, buy memoryDATAGPRSClass 32EDGEClass 323GNoWLANNoBluetoothYes, v2.0 with A2DPInfrared portNoUSBYes, microUSB v2.0CAMERAPrimary3.15 MP, 2048x1536 pixels, autofocus, dual LED flashVideoYes, VGA@15fpsSecondaryNoFEATURESMessagingSMS, MMS, Email, IMBrowserWAP 2.0/xHTMLRadioStereo FM radio with RDSGames4 + DownloadableColorsSteel, Matt BlackGPSNoJavaYes, MIDP 2.1 - H.263/H.264 player

- MP3/WAV/eAAC+/WMA player

- Organizer

- Flash Lite 3.0

- Voice memo

- T9BATTERY Standard battery, Li-Ion 1050 mAh (BL-5CT)Stand-byUp to 450 hTalk timeUp to 7 h

Comparison of VoIP software

From Wikipedia, the free encyclopedia

This list is incomplete; you can help by expanding it.

Voice over IP (VoIP) software is used to conduct telephone-like voice conversations across IP based networks. For residential markets, VOIP phone service is often cheaper than traditional PSTN phone service and can remove geographic restrictions to telephone numbers (i.e. have a "New York" PSTN phone number in Tokyo).

For enterprise or business markets, VoIP enables the enterprise to manage a single network (the IP network) instead of separate voice and data networks, while enabling advanced and flexible capabilities to the end user.

Softphones are end user based clients for initiating and receiving voice and video communications over the IP network with the standard functionality of most "original" telephones and usually allow integration with IP Phones and USB Phones instead of utilizing a computer's microphone and speakers (or headset). Most softphone clients run on the open SIP supporting various codecs. Skype runs on a closed proprietary network. "Chat" programs now also incorporate voice and video communications.

Other VoIP software applications include conferencing servers, intercom systems, virtual FXOs and adapted telephony software which concurrently support VoIP and PSTN like IVR systems, dial in dictation, on hold and call recording servers.

Cisco Wireless IP Phone 7920

From Wikipedia, the free encyclopedia

Cisco 7920 Wireless IP Phone

The Wireless IP Phone 7920 is a mobile phone branded by Cisco Systems, Inc. that communicates via IEEE 802.11b technology. According to C. Giancarlo, senior vice-president of switching, voice, and carrier systems at Cisco (as cited in ComputerWeekly.com Ltd., 2003), the 7920 was not intended to replace traditional mobile phones. Instead, he said, it was intended for use exclusively within an enterprise.

Between rechargings of the battery, the 7920 is claimed to deliver two hours of "talk time" and twenty-four hours of "standby time" (which presumably means it is switched on, yet idle) (ComputerWeekly.com Ltd., 2003). Twenty-four hours is a relatively low level of standby time compared to GSM mobile phones, which can have standby times of a week or more. This is presumably due to the greater power requirements of the 802.11 hardware and the protocol's lack of power management. In fact, the 7920, while out of range of a WAP will consume its battery in about an hour (this is because it is searching for an AP).

The Cisco 7920 supports Cisco's proprietary SCCP Skinny Client Control Protocol. Skinny is a proprietary signalling protocol provided by Cisco's CallManager. Open/Shared Key/LEAP are supported authentication methods with CCKM/WPA joining in the near future. Also, XML is going to be supported by Cisco 7920 to enable the development of applications by third parties.

Voice over Internet Protocol

Voice over Internet Protocol (VoIP) is a general term for a family of transmission technologies for delivery of voice communications over IP networks such as the Internet or other packet-switchednetworks. Other terms frequently encountered and synonymous with VoIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, and broadband phone.

Internet telephony refers to communications services—voice, facsimile, and/or voice-messaging applications—that are transported via the Internet, rather than the public switched telephone network(PSTN). The basic steps involved in originating an Internet telephone call are conversion of the analog voice signal to digital format and compression/translation of the signal into Internet protocol (IP) packets for transmission over the Internet; the process is reversed at the receiving end.^[1]

VoIP systems employ session control protocols to control the set-up and tear-down of calls as well asaudio codecs which encode speech allowing transmission over an IP network as digital audio via anaudio stream. Codec use is varied between different implementations of VoIP (and often a range of codecs are used); some implementations rely on narrowband and compressed speech, while others support high fidelity stereo codecs.

Ip Phone Features and Disadvantages

Common features of IP phones

• Caller ID
• Dialing using name/ID: This is different from dialing from your mobile call register as the user does not need to save a number to a sip phone.
• Locally stored and network-based directories
• Conference and multiparty call
• Call park
• Call transfer and call hold
• Preserving user name/ number when choosing a different service provider (not widely supported).
• Applications like weather report, Attendance in school and offices, Live news etc.

[edit]Disadvantages of IP phones

• Requires internet access to make calls outside the Local area network unless a compatible localPBX is available to handle calls to and from outside lines.
• IP Phones and the routers they connect through usually depend on mains electricity, unlike PSTNphones which are supplied with power from the telephone exchange.
• IP networks, particularly residential internet connections are easily congested. This can cause poorer voice quality or the call to be dropped completely.
• IP Phones, like other network devices can be subjected to Denial of service attacks as well as other attacks especially if the device is given a public IP address^[1]
• Due to the latency induced by protocol overhead they do not work as well on satellite internet and other high-latency internet connections.

Hardware of a stand alone IP phone

Hardware of a stand alone IP phone

Hardware-based IP phone

The overall hardware may look like a telephone or mobile phone. An IP phone has the following hardware components.

• Speaker/ear phone and microphone
• Key pad/touch pad to enter phone number and text (not used for ATAs).
• Display hardware to feedback user input and show caller-id/messages (not used for ATAs).
• General purpose processor (GPP) to process application messages.
• A voice engine or a Digital signal processor to process RTP messages. Some IC manufacturers provides GPP and DSP in single chip.
• ADC and DAC converters: To convert voice to digital data and vice versa.
• Ethernet or wireless network hardware to send and receive messages on data network.
• Power source might be a battery or DC source. Some IP phones receive electricity from Power over ethernet.

Other devices

There are several WiFi enabled mobile phones and PDAs that come pre-loaded with SIP clients or are at least capable of running IP telephony clients. Some IP phones may also support PSTN phone lines directly.

Gateway devices

Analog telephony adapters are connected to the internet or Local area network using an Ethernet port and have sockets to connect one or more PSTN phones. Such devices are sent out to customers who sign up with various commercial VoIP providers allowing them to continue using their existing PSTN based telephones.

Another type of gateway device acts as a simple GSM base station and regular mobile phones can connect to this and make VoIP calls. While a license is required to run one of these in most countries these can be useful on ships or remote areas where a low-powered gateway transmitting on unused frequencies is likely to go unnoticed.

Stun Client

A STUN client is used on some SIP-based IP phones as firewalls on Network interface sometimes block SIP/RTP packets. Some special mechanism is required in this case to enable routing of SIP packets from one network to other. STUN is used in some of the sip phones to enable the SIP/RTP packets to cross boundaries of two different IP networks. A packet becomes unroutable between two sip elements if one of the networks uses private IP address range and other is in public IP address range. Stun is a mechanism to enable this border traversal. There are alternate mechanisms for traversal of NAT, STUN is just one of them. STUN or any other NAT traversal mechanism is not required when the two sip phones connecting are routable from each other and no firewall exists in between.

DHCP Client

DHCP client may be used to configure the TCP/IP parameters and server details if network segment uses dynamic IP address configuration. DHCP client then provides central and automatic management of IP phones configuration.

Ip phone and its Elements

IP Phone

From Wikipedia, the free encyclopedia

An IP phone uses Voice over IP technologies allowing telephone calls to be made over an IP network such as the internet instead of the ordinary PSTN system. Calls can traverse the Internet, or a private IP Network such as that of a company. The phones use control protocols such as Session Initiation Protocol, Skinny Client Control Protocol or one of various proprietary protocols such as that used bySkype. IP phones can be simple software-based Softphones or purpose-built hardware devices that appear much like an ordinary telephone or a cordless phone. There also exist the possibility to reuse ordinary PSTN phones as IP phones, with analog telephony adapters (ATA).

It may have many features an analog phone doesn't support, such as e-mail-like IDs for contacts that may be easier to remember than names or phone numbers.

Elements of an IP phone

1. Hardware
2. DNS client
3. STUN client
4. DHCP client (not commonly used)
5. Signalling stack (SIP, H323, Skinny, Skype, or others)
6. RTP Stack
7. Codecs (Audio codecs such as G.711, GSM, iLBC, Speex, G.729 ,G.722, G.722.2 (AMR-WB) etc. Video codecs such as H.263, H.263+ and H.264)
8. User interface

Potential disadvantages of IP cameras

Potential disadvantages of IP cameras

The following are some of the potential weaknesses of IP cameras in comparison to analog CCTV cameras.

• Higher initial cost per camera.^[11]
• Less choice of manufacturers.
• Lack of standards. Different IP cameras may encode video differently or use a different programming interface. This means a particular camera model should be deployed only with compatible IP video recording solutions.
• High network bandwidth requirements: a typical CCTV camera with resolution of 640x480 pixels and 10 frames per second (10 frame/s) in MJPEG mode requires about 3 Mbit/s^[12].
• Technical barrier. Installation for IP Camera required a series of complicated network setting including IP address, DDNS, router setting and port forwarding. This is very difficult for most users to do alone without help from IT technician.^[13]

Potential advantages of IP cameras

Potential advantages of IP cameras

IP Video Surveillance

IP Camera
Media type	Internet Protocol
Encoding	MJPEG and MPEG4
Capacity	30+ frame/s
Developed by	Axis Communications
Usage	video transmission

Some of the most commonly cited advantages of IP-based video surveillance as compared to analog CCTV summarized in this section.

[edit]Cost advantages

• Reduced system cost and added functionality due to general-purpose IP networking equipment infrastructure.
• Lower cost of cabling in large installations (CAT5einstead of RG-59 coaxial cable).
• Reduced space requirements in large (many camera) CCTV setups because video switching and routing is done via computer and does not need physically large and expensive video matrix switchers.

[edit]Flexible image format

• Support for a variety of image resolutions including both standard analog CCTV resolutions (CIF, NTSC, PAL, andSECAM) and megapixel resolutions.
• Capability for digital zoom of high-resolution megapixel images.
• Progressive scan (versus interlaced scanning). Note that not all IP cameras operate in progressive scan mode. Progressive scan allows still images to be removed in better quality from a video feed. This is particularly true for a fast moving target, in which case interlaced scanning will introduce shutter-blind artifacts.
• Ability to select specific frame rates and resolution for each camera in a system.^[8]
• No additional video encoder hardware is required to convert analog video signals into digital data for recording onto hard drives.
• Choice of video compression codec such as Motion JPEG, MPEG-4 Part 2, or H.264.

[edit]Extensible network infrastructure

• Convergence onto new or existing IP cabling infrastructure, including sites with multiple buildings.
• Ability to use Power over Ethernet allowing for one cable to handle power and data.
• Capability for deploying with a wireless bridge.
• Ability to use legacy coaxial cables with appropriate converters.
• Ability to use fiber optic links with appropriate twisted-pair to fiber converters.
• Transmission of commands for PTZ (pan, tilt, zoom) cameras via a single network cable.
• Simple to add one camera at a time to the system.^[9]

[edit]Greater functionality

• Wireless allows the camera to be placed just about anywhere.
• No limit on resolution inherent in standard analog video formats. Megapixel cameras can far exceed image detail from conventional CCTV cameras.^[10]
• On-camera automated alerting via email or file transfer in response to video motion detection or dry-contact alarms.
• Password lockout of unauthorized personnel to prevent viewing images or altering the camera configuration.
• Support for different streaming media and compression formats to relieve transmission bandwidth and data storage requirements.
• Encryption of camera control data and audio/video data.
• Support for new embedded intelligent video motion detection (video analytics) with shape recognition and counting applied to objects, people, and vehicles.
• Integration of video surveillance with other systems and functions such as access control, alarm systems, building management, traffic management, etc.
• Remote configuration, diagnostics, and maintenance.
• Future-proof installations with field-upgradeable products due to the ability to upgrade camera firmware over the network.

Potential advantages of IP cameras

Potential advantages of IP cameras

IP Video Surveillance

IP Camera
Media type	Internet Protocol
Encoding	MJPEG and MPEG4
Capacity	30+ frame/s
Developed by	Axis Communications
Usage	video transmission

Some of the most commonly cited advantages of IP-based video surveillance as compared to analog CCTV summarized in this section.

[edit]Cost advantages

• Reduced system cost and added functionality due to general-purpose IP networking equipment infrastructure.
• Lower cost of cabling in large installations (CAT5einstead of RG-59 coaxial cable).
• Reduced space requirements in large (many camera) CCTV setups because video switching and routing is done via computer and does not need physically large and expensive video matrix switchers.

[edit]Flexible image format

• Support for a variety of image resolutions including both standard analog CCTV resolutions (CIF, NTSC, PAL, andSECAM) and megapixel resolutions.
• Capability for digital zoom of high-resolution megapixel images.
• Progressive scan (versus interlaced scanning). Note that not all IP cameras operate in progressive scan mode. Progressive scan allows still images to be removed in better quality from a video feed. This is particularly true for a fast moving target, in which case interlaced scanning will introduce shutter-blind artifacts.
• Ability to select specific frame rates and resolution for each camera in a system.^[8]
• No additional video encoder hardware is required to convert analog video signals into digital data for recording onto hard drives.
• Choice of video compression codec such as Motion JPEG, MPEG-4 Part 2, or H.264.

[edit]Extensible network infrastructure

• Convergence onto new or existing IP cabling infrastructure, including sites with multiple buildings.
• Ability to use Power over Ethernet allowing for one cable to handle power and data.
• Capability for deploying with a wireless bridge.
• Ability to use legacy coaxial cables with appropriate converters.
• Ability to use fiber optic links with appropriate twisted-pair to fiber converters.
• Transmission of commands for PTZ (pan, tilt, zoom) cameras via a single network cable.
• Simple to add one camera at a time to the system.^[9]

[edit]Greater functionality

• Wireless allows the camera to be placed just about anywhere.
• No limit on resolution inherent in standard analog video formats. Megapixel cameras can far exceed image detail from conventional CCTV cameras.^[10]
• On-camera automated alerting via email or file transfer in response to video motion detection or dry-contact alarms.
• Password lockout of unauthorized personnel to prevent viewing images or altering the camera configuration.
• Support for different streaming media and compression formats to relieve transmission bandwidth and data storage requirements.
• Encryption of camera control data and audio/video data.
• Support for new embedded intelligent video motion detection (video analytics) with shape recognition and counting applied to objects, people, and vehicles.
• Integration of video surveillance with other systems and functions such as access control, alarm systems, building management, traffic management, etc.
• Remote configuration, diagnostics, and maintenance.
• Future-proof installations with field-upgradeable products due to the ability to upgrade camera firmware over the network.