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SIP TRUNKING:
What is SIP and SIP Trunking?
SIP, short for Session Initiation Protocol, is an IP telephony signaling
protocol used to establish, modify and terminate voice, video and data
sessions. It resides in the "Sessions" Level 5 with
interoperability activities in the "Transport" Levels 2
and 3 of the OSI platform.
SIP describes
the communication needed to establish a phone call.
SIP has taken
the VoIP world by storm. The protocol resembles the HTTP
protocol, is
text-based, very open (open for all programmers who wish to develop it) and flexible. It has therefore largely replaced
older protocols (like the H.323 standard)
Because
it is a text based language, it is considered
"open source which means any programmer can
collaborate with others to help develop the
platform. The open source name where this
work is being done is "Asterisk"
(Link)
"Trunking"
refers to the physical circuitry, switching,
firmware, and software that provides
connectivity through the Telecom architecture.
"SIP Trunking" refers to the new applications,
coding and switching that establishes more
robust digital and virtual approaches to
telecommunications connectivity within the
Carrier's network.
What can SIP do for your
business?
Boost Network Traffic:
-
Eliminates the need for protocol changes or conversions
-
Provides seamless communications across multiple IP sites
-
Squeezes more capacity out of T-1 circuits using SIP compression
technology (SIP does not increase bandwidth)
Simplicity
-
Combines Voice and Data traffic on one single circuit and applies
Dynamic Bandwidth Allocation (dynamically allows bandwidth for data
to expand while bandwidth is not being used for voice. Voice has
priority over data)
-
Price based on bandwidth requirements/size, regardless of number of
voice lines.
-
Customizable call plans
Flexible
-
Scalable Bandwidth (Access)allocation, usually from 1.5 Mbps to
45Mbps.
-
Supports IP PBX functions and operations
-
Customizable and optimizable through simple Web administration
portal
Cost Effective
-
Allows for "anywhere to anywhere" connectivity, eliminating the need
for the expensive and equipment-heavy "Hub and Spoke" architecture.
-
Transparent to a variety of different types of equipment, thus
eliminating the cost of changing out of existing equipment.
-
Network- based verses LAN Based VPN and management, thus optimizing
the time and resources of the company's IT technician(s) and
eliminating / reducing the need for customer supplied VPN equipemnt.
-
Allows for the use of IP phone technology thus eliminating expensive
TDM Voice PRI technology.
-
Allows for VOIP voice compression which optimizes bandwidth usage
and possible reduction of bandwidth requirements and cost.
-
Supports
multiple application protocols, eliminating the need for additional
compatibility compliance software.
What is VoIP:
VoIP stands for "Voice over Internet
Protocol. It is simply converting and sending voice signals
originating and terminating on IP phones (or devices which turn the analog
phone signal into digital signals) over the Internet.
Benefits of an IP phone system over an
analog phone system:
-
VoIP
is driven by software programs manipulating digital signals rather than
Analog hardware equipment which has to regulate and modulate the analog
signal.
-
Voip
is more flexible and robust in creating unified messaging and call
management features without lots of equipment or switches.
-
VoIP
gives the user the ability to call anywhere from anywhere because the
phone has it own address, which is an Internet address (called
"MAC" address). The analog phone is confined to a physical address where
all the voice equipment resides.
-
Because the IP Phone is Internet-based, it comes with a Web-portal
(website) where the administrator can simply program their own phone by
simply clicking on whatever features are desired. Each Web Portal
is dedicated to the individual administrator and is log-in / password
protected.
-
Unified messaging means that the call can be directed to the particular
IP phone, to another member of the company, to a voice mail system
and/or also to the email client in the form of a "wav" file File that
can play the voice message over the computer.
-
Call
mamagement allows the administrator simple tools to track incoming and
outgoing calls, who is making the calls and where they are calling.
It also allows for simple report creation and call restrictions.
What is SIP or VOIP
Compression:
Calculating bandwidth consumption for VoIP
The bandwidth needed for VoIP transmission will depend on a few factors: the
compression technology, packet overhead, network protocol used and whether
silence suppression is used. This tip investigates the first three
considerations. Silence suppression will be covered in a later tip.
There are two primary strategies for improving IP network performance for
voice: Allocate more VoIP bandwidth (reduce utilization) or implement QoS.
How much bandwidth to allocate depends on:
- Packet size for voice (10 to 320 bytes of digital voice)
- CODEC and compression technique (G.711, G.729, G.723.1, G.726)
- Header compression (RTP + UDP + IP), which is optional
- Layer 2 protocols, such as point-to-point protocol (PPP), Frame
Relay and Ethernet
- Silence suppression/voice activity detection
How many phone lines can be compressed through each
codec?
Here is a standard being developed in the industry.
Although some companies boast that they can deliver more phones than
displayed below, call quality diminishes with every additional line.
None of the established CODEC standards will cause packet loss, echoing,
Jitter, or dropped calls. This is usually casued by network strength
and number of router "hops' between server and customer.
CODEC | # OF LINES PER T-1 | RESULT IN QUALITY
G711 | 18
| Superior over TDM
G729 |
26
| Some degradation but superior over TDM
G726 |
32 | Quality of Cell Phone call
G723 |
40
| Quality of Cell Phone Call
Here are the "nuts and Bolts" of the COdec Calculations:
Calculating the bandwidth for a VoIP call is not difficult once you know
the method and the factors to include. The chart below, "Calculating one-way
voice bandwidth," demonstrates the overhead calculation for 20 and 40 byte
compressed voice (G.729) being transmitted over a Frame Relay WAN
connection. Twenty bytes of G.729 compressed voice is equal to 20 ms of a
word. Forty bytes of G.729 compressed voice is equal to 40 ms of a word.

The results of this method of calculation are contained in the next
table, "Packet voice transmission requirements." The table demonstrates
these points:
- Bandwidth requirements reduce with compression, G.711 vs. G.729.
- Bandwidth requirements reduce when longer packets are used, thereby
reducing overhead.
- Even though the voice compression is an 8 to 1 ratio, the bandwidth
reduction is about 3 or 4 to 1. The overhead negates some of the voice
compression bandwidth savings.
- Compressing the RTP, UDP and IP headers (cRTP) is most valuable when
the packet also carries compressed voice.
Packet voice transmission
requirements
(Bits per second per voice channel) |
| Codec |
Voice bit rate |
Sample time |
Voice payload |
Packets per second |
Ethernet |
| PPP or Frame Relay
|
|
RTP |
cRTP |
|
| G.711 |
64 Kbps |
20 msec |
160 bytes |
50 |
87.2 Kbps |
82.4 Kbps |
68.0 Kbps |
| G.711 |
64 Kbps |
30 msec |
240 bytes |
33.3 |
79.4 Kbps |
76.2 Kbps |
66.6 Kbps |
| G.711
|
64 Kbps |
40 msec |
320 bytes |
25 |
75.6 Kbps |
73.2 Kbps |
66.0 Kbps |
| G.729A |
8 Kbps |
20 msec |
20 bytes |
50 |
31.2 Kbps |
26.4 Kbps |
12.0 Kbps |
| G.729A |
8 Kbps |
30 msec |
30 bytes |
33.3 |
23.4 Kbps |
20.2 Kbps |
10.7 Kbps |
| G.729A |
8 Kbps |
40 msec |
40 bytes |
25 |
19.6 Kbps |
17.2 Kbps |
10.0 Kbps |
Note: RTP assumes 40-octets
RTP/UDP/IP overhead per packet
Compressed RTP (cRTP) assumes 4-octets RTP/UDP/IP overhead per
packet
Ethernet overhead adds 18-octets per packet
PPP/Frame Relay overhead adds 6-octets per packet |
THE FOLLOWING IS BY COURTESY OF NUVOX
COMMUNICATIONS:
Contact Bill Quaglia, 888-605-2630 for
further information on, or to the get a quote from Nuvox.
Product Definition:
SIP (Session Initiation Protocol) is
a signaling service that allows for
the set up of sessions (Calls and
other communication methods). This
signaling occurs over any type of
traditional transport. (T-1,
Ethernet, others)
Premise based IPPBX systems have
been using this technology for a
number years on the station or
customer premise side of the PBX in
order to deliver enhanced voice,
video and data applications such as
private messaging, presence and
conferencing tools.
With the introduction of SIP Trunks,
Customers will be able to extend
these types of applications to the
Trunk or Public side of their
networks.
This will prove beneficial
immediately in applications where
customers have multiple locations
and have a desire to manage remote
sites and stations from the host
site.
SIP Trunks will also allow for a
foundation for future enhancements
as VoIP functionality continues to
evolve.
NuVox’s Retail SIP Trunking is a
product that offers enhanced
features and functionality
as delivered via
NuVox’s Private, MPLS IP Network
and as such, falls under the VoxIP
product portfolio. Only customers
in markets that have VoxIP will have
access to the SIP Trunking product.
NuVox’s Retail SIP Trunking Product
is designed specifically for
customers who have IPPBX systems.
(Internet Protocol enabled or
capable Premise based systems). SIP
Trunking provides these customers a
way to combine their data (Internet
access/WAN) and voice traffic into a
single pipe and access the internet
and PSTN through NuVox’s Secure,
MPLS/QOS enabled Network. SIP
trunking allows the customer to
terminate the trunk into an Ethernet
port, often saving the customer
hardware costs typically associated
with PRI or T-1 cards. Many IPPBX’s
contain codec’s that allow for the
compression of voice in order to
improve efficiencies of transporting
voice across PSTN and WAN networks.
NuVox will allow customers to
subscribe to the compression feature
for a flat rate designed to prevent
cannibalization of transport
revenue.
Product Attributes:
Dynamic Bandwidth Allocation
Silent
Suppression
Compression (optional, fee applies),
supports G7.11,G7.23, G7.26, G7.29
QOS-
Voice Prioritized over data
T.38
for enhanced faxing capabilities
Remote
and Local DID
911
and Local Call routing based on DID
physical address
Caller
ID
Network Diagram (Single-Site)
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SIP AND MPLS ADVANTAGE
THROUGH NUVOX:
SIP and MPLS - A Match Made in Heaven!
VoxNet and SIP Trunking
Application: Host/Remote site Deployments:
In order to meet customer demands in a multi- site application, Nuvox will offer remote DID service in areas that are in NuVox Footprint. NuVox’s VoxNet Gold product should be purchased when connecting multiple sites.
NuVox will improve processes to enable Local call routing and 911 routing down to the DID level. This service will only be available to SIP customers. This will allow customers to save money by not deploying multiple PBX’s at each remote site.
This environment will allow the host site to manage their remote office/trunk side extensions in a manner that is equal to those that are station side at the main location.
Depending on the particular PBX and its available features, this could include IP enabled communications solutions such as messaging, video, presence and other custom applications.
Site to Site calling over VoxNet:
Depending on the functionality of the Customer’s PBX and programming by the PBX Vendor customers may be able to make site to sit x digit extension dialing over the VoxNet Gold Connection. This is a function of the PBX, but not prohibited by NuVox VoxNet Product.
Long Distance
Long distance usage will be accumulated and billed at Host site.
Customers have the option of subscribing to NuVox Long Distance Buckets at published rates under VoxIP tariff. Overage is billed at .053.
Risk Mitigation
The Host/remote site architecture has certain risks associated with deployment in the event that the customer and/or PBX vendor chooses to manipulate the out pulsed DID number to be different than the NuVox provided DID. In the event that NuVox does not recognize the DID, it will automatically default local and 911 routing to the physical trunk group on which the call was processed. Customers should be advised of these risks and take appropriate measures to ensure the safety of their employees.
Mitigation language is included in the Tariff regarding these specifics.
Remote Extension functionality:
When deploying SIP trunks in a multi-site application, all features and access are provided by the IP PBX system at the host location. Sites are networked together via a VoxNet connection. Depending on the IPPBX type and architecture deployment, this will provide customers the ability to manage remote extensions in the same manner as those located at the host site. It also allows for the ability to implement IP enabled features across sites if purchased and enabled by the IPPBX. These features may include (but are not limited to) messaging, presence, and video conferencing. All of these features must be provided by the IPPBX.
Redundancy:
If the customer chooses to build a redundant network, a second IPPBX may be located in a data center. Co-location is an optional product which can be bundled with SIP as a solution for redundancy. Additional fees apply. This architecture is recommended for businesses that wish to assure minimum downtime for all locations.
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