Analogue telephone lines provide users with limited functionality. You can only have one telephone number per line (although you can have extensions, enabling you to have more than one handset), and you’ll only have access to basic call features. Analogue telephone use is declining in the UK, due to the increasing popularity of mobile phones and internet based telephony systems. It’s likely to continue to fall as residential customers gain access to broadband services which don’t require them to have landline telephones, and those running businesses from home are able to modernise their telephone systems. Digital Business Telephone Lines – All About ISDN Digital telephone lines were first introduced in the late 1980s. They quickly became attractive options for businesses, as they provide far more functionality than analogue lines. Digital lines enable businesses to have multiple channels. They also allow companies to allocate Direct Dialling In (DDI) numbers to different departments and individual employees, so customers can get straight through to the person they need to speak to. There are two main types of digital telephone lines in the UK: ISDN2 and ISDN30 lines. While both types of ISDN (Integrated Services Digital Network) line have similar capabilities, the key difference between them is the number of channels that they can provide. ISDN2 telephone lines provide a minimum of two channels, with the option of adding further pairs of channels as required. ISDN30 lines, on the other hand, provide between eight and thirty channels per connection, but multiple connections can be used, allowing large companies to have more than 100 channels. As discussed in our previous post, however, ISDN and PSTN telephone lines’ days are numbered. If you run a business, it could therefore be the ideal time to switch to internet based business telephone lines. Internet Telephone Lines – SIP vs VoIP If you’re researching internet based telephony options for your business, you’ll find that two acronyms will keep cropping up: SIP and VOIP. SIP (Session Initiation Protocol) isn’t actually a type of telephone system: it’s a protocol used to enable data packets to be transmitted between devices via the Internet. A SIP telephony system usually consists of internet telephone lines that are attached to a traditional onsite PBX (private branch exchange) telephone system.