Telstra SIP Connect

The major reason to move to SIP trunking is operational cost savings. Gartner estimates that SIP trunking offers savings of up to 50 percent when compared with traditional phone services. By replacing the need for confusing ISDN circuits and bypassing traditional PSTN phone lines, SIP trunking maximises Return on Investment. A SIP-VoIP solution can usually be expected to pay for itself within 12 months and long-term financial savings will also be evident through the increase in productivity given to the business. SIP trunking delivers savings in the following ways:

• Free calls between offices. SIP providers route calls between your offices over either a private network you may be running or the internet. Free calling between offices can be a huge cost-saver for businesses, especially those with locations in multiple countries.
• Better rates, particularly for international calls: Businesses can save as much as 75 percent on international calls with SIP trunking.

• Best effort v guaranteed QoS

Many service providers offer SIP products which have either Best Effort QoS or Guaranteed QoS. Best Effort is a QoS model where all the packets receive the same priority and there is no guaranteed delivery of packets. Best Effort is applied when networks have not configured QoS policies or when the infrastructure does not support QoS. Guaranteed QoS is a model where the provider guarantees that there will be sufficient bandwidth allocated to handle all traffic without degradation of quality of service. Guaranteed QoS may require a dedicated SIP trunking solution or private cloud.

• Mobile failover as redundancy

• Bandwidth

In Australia, many small businesses with 5 or fewer trunks, and branch offices, will be able to provision their SIP trunks over the same broadband internet connection as standard internet traffic.

However, be aware that voice packets are sharing bandwidth with internet traffic, so the volume of internet traffic and the bandwidth available become critical factors that determine quality of voice calls.

To avoid the risk of dropped packets and delayed transmission which will result in a noticeably poor quality of service for end users and customers, during periods of peak usage ensure there is enough bandwidth allocated.

If internet and voice traffic are light, a high bandwidth/low cost connection can be a very good solution for small businesses.

Businesses that need over 5 trunks and have moderate phone traffic will benefit by having a dedicated network connection.

The best option would be a private MPLS link which supports QoS and eliminates contention.

The next best type of connection would be a dedicated internet connection for voice. Most call quality issues arise in the last mile or the connection between the customer and Internet Service Provider. Keeping standard internet traffic and voice traffic separate will resolve the issue of voice packets having to compete for the same bandwidth as all other internet traffic.

The best option for businesses that need 20+ SIP trunks is an MPLS network with guaranteed QoS, and the ability to deliver multiple unified communications solutions like video conferencing, instant messaging, multi-media file sharing, and cloud-based applications in real time.

For enterprise businesses that experience large phone traffic, the optimal solution would be to install a dedicated fibre connection between the premise and the SIP provider. The same connection can be used to provide internet access and a QoS supported voice solution.

Although such a solution could be more expensive than typical DSL or cable connections, it has the added benefits of long-distance savings, elimination of copper trunks at remote offices (with SIP, those numbers can port to the corporate office) and better use of bandwidth.

Multi-Protocol Label Switching is a private circuit used to connect multiple sites and remote workers. It was created to increase the forwarding speed of routers and has evolved to become vital in the building of large IP networks.

MPLS does not use the public internet which means the business retains complete control of its traffic, and is able to add priorities to types of traffic such as data or voice. This means MPLS is a Quality of Service (QoS) network delivering faster speeds and a totally uncongested network.

MPLS solutions are flexible in nature so network designers can easily decrease the number of ‘hops’ to and from different network points making for a rapid response time.

To get the most out of SIP Trunks they will need to be placed over a QoS network such as MPLS.

The other method of utilising SIP is over the public Internet.

SIP over the public Internet may be suitable for businesses with light phone traffic.

If the connection is going to be used to send other types of traffic such as video or email, there has to be enough bandwidth to cope, or there has to be a way for voice traffic to be prioritised over all other traffic.

Having a dedicated separate internet connection for voice traffic would solve the problem of contention at the local network level but not at the Internet Service Provider level, and although this is a better solution, QoS still cannot be ensured and there may be some loss of performance unless carefully monitored.