If you both live at 2 different locations, bring the laptop to your location and try it on your dial up. If it behaves, then its likely a bad connection.
If you live in teh same house hold, then plug the laptop in to your dial-up cable that normally is connected to your desktop and see if you have better connectivity.
Bad phone cords, bad (old copper lines ) can cause problems if the lines are from the 70's or 80's or even older. A good indicator of poor lines is a lower than normal sync speed in which the ISP is hosting a 56k service and you are connected at only 33k, 26k, 19k, or even worse 14k.
My house has old 1970's telephone poles leading to it and up until broadband came to my area, my maximum connection was 26k on a good day, but usually 19k .... and boy was that painfull!!!!! ISP was hostinga 56k service and I was not able to get full bandwidth, and it would disconnect a lot since the lines were poor and noisy.