Written by ISDN and SIP trunks are the main options for companies of all sizes to have their calls delivered into their business. So what are they and what are differences between them?
ISDN (Integrated Services Digital Network) has been the go-to option for businesses for many years, and while it is scheduled to be deactivated in 2025, there are still some good years left in this technology.
SIP (Session Initiated Protocol) transmits signals via IP telephony – a technology that has grown in reliability over the years and is now the preferred method for an increasing number of businesses.
ISDN is a scalable option for small and growing businesses, starting with just two voice channels for simultaneous calls, but quite easy to increase to eight or more lines using an ISDN30 circuit – each of these supports up to 30 simultaneous calls, and you can add extra circuits as needed. Existing copper cables can be used with ISDN circuits, so there are no infrastructure issues, but by transmitting the data digitally you typically get a more professional, business-standard call quality.
SIP Trunks
SIP trunking is rapidly becoming the mainstream option of the two, particularly among companies that are preparing well in advance for the 2025 shut-off of BT’s core ISDN infrastructure, by which time all business lines are expected to migrate to IP protocols. Existing telephone numbers can be ported over to SIP, so there’s no need to change your company literature or ask customers to dial into an unfamiliar-looking IP dialling code.
Whereas ISDN delivers data over voice lines, SIP works the other way around, using high-speed internet connections to transmit your voice data as well as your internet file transfers, emails and so on. ISDN has some good years left in it and is still a great option for small businesses and fixed line numbers, while SIP trunking offers good scalability.
SIP Advantages
SIP has the advantage of providing an ‘automated failover’ which means that if the SIP trunks cannot see your phone system then it automatically points the calls to a pre-determined set of numbers. This could be back-up lines coming into your system, to another site or simply out to mobiles. Indeed we find that many clients retain some ISDN for this failover produce – the good news is that it costs in as your overall bill will be cheaper despite having this disaster avoidance in place.
SIP is typically cheaper than ISDN which is another reason it is being so widely adopted by the business community.
Whichever solution you prefer Workflow are here to help with all of your questions and aim to save you money while improving call quality at the same time.