@rustybob There will be a bottleneck somewhere, and obviously this is usually your line. In the case where you are talking to a particular web server, that server or the pipe into it could be overloaded though. If your particular ISP has lots of capacity (and that also has to apply to partner carriers if the ISP uses e.g. BTW or TTB for access from customers) into its network and to the wider internet then as long as that's enough considering the weight of traffic from their user base then its good enough. So you want an ISP that either has high capacity links or low-usage customers or few customers. Traffic capacity obviously has to be relative to the number and type of customers that the ISP has. Networks that offer QoS (quality of service) can prioritise some traffic types over others, so that packets get sent first and jump over queues. This reduces latency dramatically and can improve throughput.
To answer your question about how to find out. If your ISP publishes congestion reports then that's a plus. ;-) Otherwise it’s probably a matter of digging around, asking users, rumour mill, or perhaps looking at the results of those speed testers that record which ISP is in use, although these are very difficult to interpret as you can't know how long lines are or whether users’ modems are any good. ISPReview is worth a look as it has users' speed opinions in it. Others might have some constructive suggestions.
Thanks Weaver. I've put my investigative hat on
and it looks like I'll be OK if I go with BTW.
I'm on the Chesterfield exchange an pre July 2016 people with say a normal connection speed of around 50 or 60mb were experiencing speeds of only 7.6Mbps at 9.00pm. BT acknowledged a congestion issues and added further capacity in two stages - 14/07/16 and 22/07/16. Post these dates, the same users are quoting speeds of 50Mbps at 9.00pm so it looks like BTW would be a good option.
With regard to TT, I've a friend with them who can loose some of his speed at certain times. Was never really sure of why but I now have my suspicions, assuming I'm not jumping to the wrong conclusion? Probably need to do a little more research on TT though if I'm honest. With regard to Vodafone, there seems very little info out there. Given previous comments I'm guessing they would be OK, however, I've been trying to use their online 'chat' facility all day and keep getting a response of "
We're sorry, all our advisers are busy - Unfortunately none of our Advisers are available to chat to you at this time. Please try again shortly". Not great if it was urgent and sort of makes the service pointless!
I should probably have a look at Sky too given Sky, TT and Vodafone all have an LLU presence.
Thanks