The role of the ISP

This may seem obvious in view of the Forum description. But I am a lummock. If I Skype with A.N.Other does the traffic pass thru my ISP ? Or is it somehow independent of my ISP? I ask only about Skype.

I get excellent service from my own ISP and good Skyping with all friends except for one in the USA. Nor can I get e-mail to that person nor to their Google-mail account either. The stuff is bounced.

I think e-mail, g-mail, hot-mail and any other mail, and also Skype, go through that person's ISP's server. Am I right?

Because the Skype stuff is part of the broadband traffic (IP), it has to pass through the services which you and he have, but it isn't really being greatly 'handled' by the ISP as it is mostly a question of offering a path between the two ends.
Email can be a little different, as you often (but not invariably) use the ISP as a part-way house.
I wouldn't expect any problem with sending to a gmail address, as that is effectively independent of the ISPs at either end, so, if you can send to other USA recipients which have gmail addresses, there would have to be something odd for just one to be blocked - there may be a clue in the detail of any bounce messages you recieve.

Edited by dandnsmith (Sat 14-Apr-12 08:26:09)

Skype is a potentially awkward example as it is a peer to peer system using other Skype users as part of the deal, but in general your ISP and their ISP's routers and switches will be handling the Skype and other traffic end to end.

Email is potentially a different game as it's a store and forward setup that could involve several servers at your ISP and at the other end's ISP. Or it could involve both ends logging into something like Gmail.com to use web based mail in which case you're back to the simple traffic passing scenario.

This isn't correct. Skype initiates the session, and hence knows who is online, and their IP addresses and user IDs. Once a conversation has been started however, Skype hands over the conversation traffic handling to the peers themselves, who send it to one another. But the central session management is there, nevertheless, and has to be, since if it were not, there would be no way of involving newly logged on users as they appear.

All internet services are subject to the session being handled by a third party - only when you connect *directly* from one machine to another using the other party's IP address are you out of the view of the service provider - although of course you are still visible to the broadband ISP, but all they could see on their servers would be packets arriving and leaving - they would have no involvement in the session as such, and wouldn't know if you were texting or speaking to the other parties, or anything else, unless they put a packet sniffer on your connection of course.

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