Dropped line

[#1]

My wife is in the US at the moment and today when I was talking to her the line went silent but didn't drop.  I rang off and got the dial tone and when I dialled again all I got was silence   I just tried again but got no ring tone but apparently it was ringing at the other end, and this time I managed to talk to my wife (previously she'd answered but got silence)  Non US numbers seem to be working OK.
Has anyone else experienced this?

[#2]

@SteveA,
Let us know if this becomes a regular problem.
A quick test hasn't indicated any issues.

[#3]

She's home now but she'll be phoning family again soon we'll keep an eye on it.

[#4]

Just done it again - line went dead (no dial tone) during a phone call. Rang off, got dial tone, attempted a redail - went to a dead line. Tried again and got through.
This is to a totally different number to the one I was dialling.

[#5]

Our tests aren't finding a fault although that's not to say there isn't one.
We'd need you to go through the steps listed here http://www.plus.net/support/phone/troubleshooting.shtml