What happens when changing ISP? What does the ISP do?

EssexExile

tripled said:

I have a fairly rudimentary understanding. It very much depends on the infrastructure in your area, and the providers and technologies you are switching between.

If your house is connected to "traditional" Openreach (ex-BT) infrastructure, Openreach own the cabling from the master socket in your house, through the cabinet in your street, to your local telephone exchange. Inside the exchange, Openreach have equipment that enables your broadband service and connects to a "backhaul" cable that will carry your internet data between the exchange and their central network. Your traffic is then forwarded on to your ISP's own data network. This service is made available on a wholesale basis only to ISPs (you cannot take out a contract directly with Openreach) and the wholesale charges are regulated. 

If you are changing between broadband suppliers that use Openreach's equipment, it is basically a set of configuration changes. Your ISP will notify Openreach of the transfer, set up your billing account and access credentials on their systems, and provide you with the router settings. Whenever your router connects, it will be allocated an IP address (the internet equivalent of a phone number) belonging to your chosen ISP and the traffic will be routed across the correct networks. Your new ISP will pay charges to Openreach, while your old supplier stops paying Openreach and closes your account.

It may be slightly different if your exchange is "unbundled" - this means that other providers (such as Sky) have put their own equipment in the exchanges alongside Openreach's, although Openreach still own the cable between the exchange and your house. If you switch between these providers, then someone may have to come out to the exchange or cabinet and physically swap your connection over to the new provider's equipment.

I remember years ago we were with Freeserve/Wanadoo/Orange and at one point they swapped from using BT equipment in the exchange to using their own. That's when we stopped using them because the service went downhill very quickly.

tripled

debitcardmayhem said:

Openreach is not ex-BT …

Just to clarify, I wasn't trying to say it was. It is the infrastructure that is "ex-BT', being no longer directly owned or managed by a division of BT Group, but instead by Openreach Limited, a separate, firewalled, independently governed subsidary company that does not use BT branding. It provides a number of ISPs (not just those within BT Group) with supposedly equitable wholesale access to its network and infrastructure. Perhaps "aka BT" would have been a better term.

Heedtheadvice

You have an odd view of company structures

You state ".....being no longer directly owned or managed by a division of BT Group....."

From Openreach's own website

'We're a wholly owned subsidiary of BT Group.....'

so yes separate management etc but still part of the group  much like BT, EE and Plusnet.