ISDN is fast becoming a technology of the past with the service set to be phased out by 2025 and replaced by SIP, an IP based service delivered over broadband and/or leased live circuits.

Here are some considerations that organisations need to think about when planning a move away from ISDN to SIP.

This is a great time to define your business needs and document your existing communications connectivity, for example, how many phone lines and numbers you have and where they lead to or terminate. Consider too what currently happens to calls if your lines are busy – are they queued or handled by voicemail?


Because SIP trunks are more flexible and versatile than ISDN this is also the time to map out how you could use and benefit from the new features that will be available once you have made the switch. This would include for example updating your disaster recovery and business continuity plans as SIP trunks can have user-configured failover to secondary circuits for resilience and/or call redirection to alternative locations. At the same time, you can assess your remote and homeworking plans so that employees working outside of the main head office have access to free ‘on-net’ calls due to the fact they are on the same dialling plan.

SIP is perfect for seasonal business or planned changes in call activity volumes such as a sales and marketing campaign so you can factor these requirements in with your supplier – and remember, unlike ISDN with SIP you only pay for the services you use and not for spare trunks to sit idle when they are not required.

Many PBX phone systems designed after 2007 are compatible with SIP but today many users are ditching legacy, hardware-based telephony solutions for cloud or hosted telephony and now is a great time to examine the deployment benefits of these new solutions. Again, with cloud telephony, you only pay for what you use which is perfect for fast-growing organisations and those with seasonal requirements.

What Amillan can offer … 

Amillan has the skills and support level to ensure you always have the services you need up and running. We possess the ability to ‘port’ existing numbers over to your SIP trunks, a vital consideration for business continuity and customer confidence.

Contact Amillan today, so that we can guide you through your transition to SIP and VoIP.

Original article can be found here: The SIP Series (III): How do I replace ISDN? (2017)

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