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6 things you need to know about SIP Trunking

6 things you need to know about SIP Trunking

SIP trunks are more than just a replacement for your telephone lines. Whilst they are the most obvious candidate when it comes to reliability and taking a step towards the cloud, there is a lot more to SIP trunking. Here are 6 key things you should know about SIP trunking before making your decision to go down the SIP route.

1.  Several ways to receive immediate ROI

SIP trunking and cost optimisation go hand in hand. When building a business case for SIP, the monthly rental charges prove far more cost-effective than your current ISDN lines. It’s also important to factor into your total cost of ownership (TCO) that SIP trunks do not require installation charges the first time, or any time you need to add or remove SIP users.

For each pair of ISDN trunks that you need to install, move premises or add new users to, you should expect to save £250 or more each time you scale up. SIP does not require any physical infrastructure to be installed to your premises. Hence, removing the costs for time and materials.

Another long term business benefit of SIP is on-net calling. As more and more of your sites adopt SIP trunking, this reduces the cost of calling your colleagues. Rather than having to dial from landline to landline and occurring local and national call charges, SIP trunks connect your sites over the internet.

Functionality such as disaster recovery and intelligent call routing also removes any unnecessary downtime from your business. If you cannot answer the phone, you cannot process customer transactions or meet your support SLAs. When disaster recovery scenarios are setup, calls can be automatically rerouted to other sites that are not suffering from the same disaster scenario. You should refer to recent power outages or connectivity failures to see if you can build in time lost into your TCO.

2.  Security

Common SIP myths and misconceptions have recently been totally debunked. Despite uptake of cloud technologies experiencing exponential growth, IT and Security Managers still adopt new technologies with a level of caution. A regular assumption that because calls occur over the internet, they are unsafe.

SIP traffic routed over public internet is not as secure as routing calls over a private connection. However, by ensuring your connection follows security best practices, you don't need to worry. SIP trunks simply carry the call data. So, if your underlying connectivity is secure, the data transmitted across is will be just as secure. In most scenarios, we would recommend a private connection, with segregated bandwidth for SIP calls. You can read more about how network performance impacts cloud technology here.

3.  Scalability

There is no upper limit when provisioning SIP trunks. Of course, this does depend on your network requirements. As you add more SIP users to your trunk, more concurrent sessions are made available via your SIP VLAN. Where bandwidth is readily available, or can be made available, more SIP sessions just need to be added to your existing setup.

The same applies for scaling down. Either permanently or seasonally, you can decrease the amount of SIP sessions you need as your business changes. This saves you from overpaying for services that are not in use. A common scenario with ISDN and PSTN lines, most of the time you keep the lines running but unused for the next time you need to utilise them.

4.  Legacy services

ISDN and PSTN services primarily carry voice traffic. But, make sure you don’t overlook other services like fax, card machines and alarms or any other services that are connected to your phone lines.

Firstly, you should conduct a physical audit around your sites to note down exactly what is connected to your phone lines. If it’s just the phone system(s), you are ready to go. If you find any analogue services like a franking machine, you will need to prepare for continuing these services over SIP. Often, we deploy adapters and gateways when services are incompatible with SIP. However, most modern versions of these services now include their own SIP connector.

5.  Network

Your network and connectivity are the ultimate enablers of SIP performance. With a solid network providing the backbone to your SIP calls, you shouldn’t ever have to worry about a dip in quality.

When network configuration is not ready for SIP traffic, or bandwidth has not been made exclusively available, SIP typically suffers as it has to compete with other applications and services.

Latency, jitter and packet loss are common symptoms of SIP trunks suffering from lack of network readiness. Latency causes repeated speech in VoIP calls. Jitter results in patchy audio quality. Packet loss often results in delayed speech – when packets are not transmitted in full, the entire speech of the caller won’t make it through.

Ensuring you have enough bandwidth available is simple. By following the rule of 1MBps per 10 concurrent calls, you can quickly work out how much bandwidth you need to dedicate. When planning for SIP, ensure you factor in any lead time of upgrading your connectivity.

For network services and configuration, most providers help out by performing a network readiness assessment for those IT departments without specialist resource.

6. Interoperability

When thinking about moving to SIP, it’s important to ensure your PBX is SIP-compatible. SIP is such a widely adopted technology that most PBXs in the modern workplace are interoperable. If your existing PBX is Mitel, Avaya or Cisco, it’s likely that you can replace your current phone line infrastructure with SIP.

However, this little snippet of information is an absolute must before you start to plan your migration.

By making a relatively small investment in SIP, the benefits outlined will help you make the decision to move to SIP, but you may not be fully ready to plan and migrate just yet. To check whether your PBX is SIP-ready, and to read more about network readiness, check out this SIP trunking installation requirements guide or contact us for help.

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