Email, VoIP and Wired and
Wireless Networks
By Sam Heighes
Definitions
• Store and forward is a telecommunications technique in which information
is sent to an intermediate station where it is kept and sent at a later time to
the final destination or to another intermediate station.
• An address book or a name and address book (NAB) is a book or a
database used for storing entries called contacts.
• An attachment is a file that you want to include with your email message.
You can add many attachments to an email message.
• Carbon copy (Cc) – enter it here if the email needs to be seen by this
person but is not addressed to them.
• Blind carbon copy (Bcc) – enter it here to prevent other recipients knowing
you’ve sent it to this person.
Print screen of an email message
Advantages of Emails
• It’s quick and easy to use. An email typically arrives seconds after it’s sent.
• Unlike letters, a single email can be sent to multiple people at no extra
cost.
• Emails can have text, images, audio and video in them.
• Files can be sent with an email, as attachments.
• Emails can be forwarded. This is when you send an email you’ve received
on to someone else.
• All email providers work together. Regardless of provider, if you have a
person’s email address you can send them an email.
• It doesn’t cost to send an email. The costs are covered by your internet
service provider (ISP) or by advertisements.
Disadvantages of email
• Because it’s so quick, it’s easy to send an email you might later regret, or to send one to the
wrong person entirely.
• Emails can be misunderstood. A rushed email may be interpreted as rude by the recipient.
Emoticons can help but are best avoided in formal or professional emails.
• Email overload - because it’s so easy to send an email it’s possible to receive lots of emails every
day, sometimes far too many to deal with.
• Spam and junk mail – emails you haven’t asked for and don’t want. A good spam filter will stop
most of these from reaching your inbox but sometimes mail that isn’t junk may slip into your junk
mail unnoticed. It is always worth checking your junk mail if an email you are expecting doesn’t
arrive.
• Attachments may contain viruses that can damage your computer.
• There is no way of knowing if a recipient received an email unless a read receipt is used. A read
receipt is sent to the sender when the recipient opens the email.
• It’s rare to receive an instant response to an email as they may be treated as less urgent than a
phone call.
Simple Mail Transfer Protocol (SMTP)
• Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail
(e-mail) transmission. First defined by RFC 821 in 1982, it was last updated in
2008 with the Extended SMTP additions by RFC 5321 - which is the protocol in
widespread use today.
• SMTP by default uses TCP port 25. The protocol for mail submission is the same,
but using port 587, and SMTP connections secured by SSL, known as SMTPS,
default to port 465.
• While electronic mail servers and other mail transfer agents use SMTP to send
and receive mail messages, user-level client mail applications typically use SMTP
only for sending messages to a mail server for relaying. For receiving messages,
client applications usually use either the POP3 or the IMAP.
• While proprietary systems (such as Microsoft Exchange and Lotus Notes/Domino)
and webmail systems (such as Hotmail, Gmail and Yahoo! Mail) use their own
non-standard protocols to access mail box accounts on their own mail servers, all
use SMTP when sending or receiving email from outside their own systems.
Post Office Protocol
• In computing, the Post Office Protocol (POP) is an application-layer
Internet standard protocol used by local e-mail clients to retrieve email from a remote server over a TCP/IP connection. POP has been
developed through several versions, with version 3 (POP3) being the
current standard.
• Virtually all modern e-mail clients and servers support POP3, and it
along with IMAP (Internet Message Access Protocol) are the two most
prevalent Internet standard protocols for e-mail retrieval, with many
webmail service providers such as Google Mail, Microsoft Mail and
Yahoo! Mail also providing support for either IMAP or POP3 to allow
mail to be downloaded.
Internet Message Protocol
• The Internet Message Access Protocol (commonly known as IMAP) is an Application Layer Internet protocol that allows an e-mail
client to access e-mail on a remote mail server. The current version, IMAP version 4 revision 1 (IMAP4rev1), is defined by RFC
3501. An IMAP server typically listens on well-known port 143. IMAP over SSL (IMAPS) is assigned well-known port number 993.
•
• IMAP supports both on-line and off-line modes of operation. E-mail clients using IMAP generally leave messages on the server
until the user explicitly deletes them. This and other characteristics of IMAP operation allow multiple clients to manage the same
mailbox. Most e-mail clients support IMAP in addition to Post Office Protocol (POP) to retrieve messages; however, fewer e-mail
services support IMAP.[1] IMAP offers access to the mail storage. Clients may store local copies of the messages, but these are
considered to be a temporary cache.[2]
•
• Incoming e-mail messages are sent to an e-mail server that stores messages in the recipient's e-mail box. The user retrieves the
messages with an e-mail client that uses one of a number of e-mail retrieval protocols. Some clients and servers preferentially use
vendor-specific, proprietary protocols, but most support SMTP for sending e-mail and POP and IMAP for retrieving e-mail, allowing
interoperability with other servers and clients. For example, Microsoft's Outlook client uses MAPI, a Microsoft proprietary protocol
to communicate with a Microsoft Exchange Server. IBM's Notes client works in a similar fashion when communicating with a
Domino server. All of these products also support POP, IMAP, and outgoing SMTP. Support for the Internet standard
protocols[citation needed] allows many e-mail clients such as Pegasus Mail or Mozilla Thunderbird to access these servers, and
allows the clients to be used with other servers.
History of Email
• Ray Tomlinson is credited with inventing email in 1972. Like many of
the Internet inventors, Tomlinson worked for Bolt Beranek and
Newman as an ARPANET contractor. He picked the @ symbol from the
computer keyboard to denote sending messages from one computer
to another. So then, for anyone using Internet standards, it was simply
a matter of nominating name-of-the-user@name-of-the-computer.
Internet pioneer Jon Postel, who we will hear more of later, was one
of the first users of the new system, and is credited with describing it
as a "nice hack". It certainly was, and it has lasted to this day.
VoIP acronym
• VOIP Voice over Internet Protocol
• VOIP Voice over Internet Packet
• VOIP Video Over IP (Internet Protocol) Plugin (software)
Definition of VoIP
• voice messaging technology: a technology that enables voice
messages to be sent via the Internet, often simultaneously with data
in text or other forms.
Software required of Codec
• Codecs are utilities that are required to read a digital media file's
streams. In order to properly stream a digital media file, a user's
computer must be equipped with all the necessary codecs. For
instance, it is possible that a digital media file cannot be streamed
through a media player although its format is supported by the
application. It is also possible that a user can stream a digital media
file's audio, but not its video (or vice versa). When this occurs, users
should analyze the digital media file with codec information software.
In addition to indicating which codecs are required to stream a digital
media file, codec information software can also be used to obtain the
necessary utilities.
Internet Packets
• VoIP endpoints usually have to wait for completion of transmission of
previous packets, before new data may be sent. Although it is
possible to pre-empt (abort) a less important packet in midtransmission, this is not commonly done, especially on high-speed
links where transmission times are short even for maximum-sized
packets. An alternative to pre-emption on slower links, such as dialup
and digital subscriber line (DSL), is to reduce the maximum
transmission time by reducing the maximum transmission unit. But
every packet must contain protocol headers, so this increases relative
header overhead on every link traversed, not just the bottleneck
(usually Internet access) link.
Hardware need for a VoIP call
• Above all else, VoIP is basically a clever "reinvention of the wheel." In
this article, we'll explore the principles behind VoIP, its applications
and the potential of this emerging technology, which will more than
likely one day replace the traditional phone system entirely.
• The interesting thing about VoIP is that there is not just one way to
place a call. There are three different "flavors" of VoIP service in
common use today
Type
UTP/STP
Coaxial
Fibre Optic
Infrared
14 Tera bits per
second
115 Kbit/s
Maximum
Range
160km
120m
Benefits
Quick
Cheap
Limitations
Expensive
Low Bandwidth
Example of how
it is used
Telephone
Exchange
Bluetooth
Microwave
Satellite (high
frequency to 50
GHz range,
radio signals)
Details
Maximum Data
Transfer Rate
100 Mbps
1 Gbit/s
1cm
6,000km
Advantages and Disadvantages of Wireless
Network
Advantages
Disadvantages
• Easily integrated into existing wired-Ethernet
networks.
• Access and accessibility improved.
• Backwards compatible as standards improve.
• Speed of installation.
• Cost Savings.
• Disadvantages of Wi-Fi.
• Transmission speeds can fluctuate.
• Conflict of ‘standards’.
• Security
LAN and WAN
• LAN- A local area network (LAN) is a computer network that user
interconnects computers in a limited area such as a home, school,
computer laboratory, or office building using network media.
• WAN- A wide area network (WAN) is a network that covers a broad
area (i.e., any telecommunications network that links across
metropolitan, regional, or national boundaries) using private or public
network transports.