What are the benefits of moving from ISDN to SIP?

{ Posted on May 06 2014 }
Categories : VoIP

Over the past few years, we’ve seen a significant increase in the number of enquiries from resellers whose customers are looking to move from traditional PBX and ISDN to SIP trunks. But why are they making the move?

Moving to SIP

Moving to SIP


SIP trunks are often promoted as a cheaper alternative to IDSN as they have lower setup costs, call charges and price per channel. However, this often depends on many factors, such as the customer’s usage and choice of the underlying connectivity.


SIP trunks are a fully scalable telephony solution. You can easily purchase additional SIP trunks as and when they are required, for a low monthly fee. ISDNs on the other hand are available as either a 2 or 30 channel based solution, with a minimum of 8 channels for ISDN 30.


While customers can usually make cost savings by using SIP trunking solutions, resellers are also able to earn significant margin. The virtual nature of SIP means it’s a relatively inexpensive service to provide and, when compared to the cost of ISDN trunks, resellers can easily make margin from each trunk and from the call revenue generated. If they provide a complete solution they can also benefit from the underlying connectivity charges.

At Entanet, we ensure our SIP trunks are simple to price and buy so that you can focus on the call management value-add services their domain experience brings.


SIP is carried via an IP based platform that’s able to support multiple services and helps resellers sell and promote converged solutions from a single supplier. This virtual nature of SIP trunks means that inbound calls can be easily re-routed to any alternative location either by sending the call to an alternative SIP end point or to an alternative PSTN phone number, often at no extra charge.


The flexible and virtual nature of SIP trunks makes them ideal for disaster recovery strategies. Incoming calls can be easily and almost immediately transferred to an alternative number such as a mobile or to alternative premises, providing business continuity. With traditional solutions such as an ISDN this would not have been possible as the ISDN is installed to a physical location and the affected company would likely have incurred significant downtime and additional costs.

In fact, Entanet customers can specify an alternative location as an auto failover solution by providing a DNS SRV record to send calls to. SRV is a type of DNS record. It allows you to specify where traffic goes based on a combination of priority and availability. It is similar in functionality to MX records for email.


Reliable Internet connectivity is becoming increasingly critical to businesses. Therefore more and more businesses are opting for guaranteed connectivity solutions which include backup options and SLAs like leased lines. Where this is the case, SIP trunking is arguably more reliable than an ISDN line.


Are you interested in adding SIP Trunks to your portfolio of products? If so, get in touch!

Post a Comment