SIP trunk technology is available in different packages. Whereas outdated ISDN services served as simply the phone line, SIP offers several varieties. Each package is designed to slot into your communications strategy. This list identifies the five specific packages that SAS bundles together when offering SIP services. These are split into user packages and group packages, providing different functionality at each level.
SIP trunking standard
These are essentially users that are configured on your PBX. You can add as many SIP trunking standard users to your SIP service as required. If you have 5 or 5,000 users, the cost for providing users with SIP calling ability does not change. As SIP operates a concurrent call model, these users effectively remain idle – therefore not chargeable – until a call is initiated.
Once a call is initiated, this counts towards one of your concurrent call quotas. When the call is terminated, the user goes back into idle until used again. This scenario can occur as many times as it needs to. As long as your concurrent calls do not exceed their limit, SIP trunking standard users could be infinite.
SIP trunking disaster recovery
This package is also for SIP users, rather than groups. Here we see the addition of built in disaster recovery functionality. Typically, this package is applied to the most important numbers in a business. The types of numbers that would have a negative business impact if calls were not receivable. Good examples here are the number that hosts your auto attendant or the group number for your receptionists.
For instances where the PBX suffers a fault, your WAN fails or the power is down at one site, automatic business continuity can kick in.
Functionality includes Call Forward No Answer and Call Forward Not Reachable.
Call Forward No Answer recognises a set response time has breached its threshold and must reroute to elsewhere. This could be another site, a user’s personal mobile or perhaps your disaster recovery site. This is ideal for disaster recovery scenarios where some users may be in the office but cannot answer all calls.
Call Forward Not Reachable removes the wait time. This feature automatically detects that there is a break in service (PBX, WAN or power) and immediately reroutes your incoming calls, just like in the Call Forward No Answer scenario. This is perfect for any genuine disaster as no time is lost trying users that are not able to access the phone.
A trunk group is required per SIP trunk connection. Think of this as the main bearer on your ISDN setup. From here, the general control of your SIP service is operated. Each trunk group comes with Call Forward Always and Call Forward Not Reachable.
Call Forward Always allows every single call into your business to be transferred elsewhere when turned on. Ideal for period where your business shuts down – like over Christmas or Easter.
Call Forward Not Reachable operates the same as in the SIP trunking DR scenario, but applies at group level, to all DDIs and extensions associated with that trunk group.
Call Forward options in this package apply to the entire trunk. This means all numbers within the trunk will be sent to the same forwarding destination. This is ideal when all numbers will divert to the same place, rather than needing to be changed to individual numbers.
The amount of SIP trunks to be provisioned represent your concurrent calls. Just like with ISDN installations, the number of trunks you order, the amount of calls you can make at any one time.
There is no minimum order for SIP trunks, but you will need at least one to facilitate a call. Balancing a business case for SIP trunks becomes easy when ordering SIP trunks as you will likely require less SIP trunks than you had ISDN channels available.
Take note of how many calls are being made in and out of your business at any one time to calculate the amount of concurrent calls you need. Make sure you evaluate over peak periods. If between 9am and 10am, you’re call traffic dramatically differs to the lunch period, make sure you take the highest amount of calls. Selecting the correct amount of concurrent calls is crucial when choosing SIP trunking packages.
Even if you have 500 users, you don’t necessarily need 500 SIP trunks. Your business only needs as many SIP trunks as it will possibly make concurrent calls.
Bursting SIP trunks
When periods of unpredicted high call volumes occur, SIP trunks can be configured to burst. This means when you exceed your concurrent call capacity, the network will know you have reached maximum capacity and proactively make another SIP session available.
Choosing a bursting SIP trunk over a standard SIP trunk is advisable for businesses that have the potential to experience higher than usual call volumes based on variable scenarios. For example, a tech support division of a mobile phone retailer may receive unusual call levels if there is a product recall or doctor surgeries if there is a contagious virus in the local area.
If your business has the possibility of needing to scale up to manage unusual call activity, bursting SIP trunks provide the automatic option. This removes the delay of ordering and configuring more trunks. During this time, you will have customers or suppliers unable to reach your business.
To get started ordering your SIP trunk packages, or if you need help deciding which package is best for you, we are here to help. SAS have experience implementing these packages across a diverse range of industries and business sizes. To continue your SIP conversation, why not book a meeting, where one of our SIP experts will be happy to help you.