Sky accounts - error 100 or 104

We have multiroom in our house. My sky HD box, in my room, the little green light next to the telephone symbol, isn't lit. I have been able to access mums Sky account details on it, via the services button on the sky remote.

My mums box, in the livingroom, has the little green light next to the telephone symbol lit. She can't access the account on her box. It's coming up error code 104, or more recently 100. What do these error codes mean, and how can we clear them, so she can access the account? Is that little green light next to the telephone symbol a factor?

And, how can we get that green light next to the telephone symbol off?

http://helpforum.sky.com/t5/Archived-Discussions/Error-code-104/td-p/583650

Put simply, check your phone for a 1571 answerphone message..
..it's blocking the Sky box from 'phoning home'.

I thought the Sky+HD boxes 'phoned home' just using t'internet these days?

One thing that used to cause me all sorts of problems was that my landline was a withheld number and for ages Sky couldn't figure out why it couldn't 'phone home' only until an engineer came out and put 1470 somewhere in the engineer menu and from that moment on it worked...

I'm pleased to say that the issue has been resolved. Many thanks for the assistance.

We'll pop an invoice in the post..