Windows 7 Home 32bit Activation

[#1]

I've replaced the hard drive in an oldish computer after the old one went pop.
I've done a brand new install of Windows 7 32-bit Home Premium, but the activation key won't work online.
The telephone number it gives me for UK activation's is 0800 018 8354, but when I call it it's a flat tone (number unavailable).
I tried the slmgr /upk and slmgr /ipk commands, which reported the key code is now accepted, but windows itself is still telling me I need to activate online and then failing.
Does anyone know what's up with the telephone number, or another method I can try? I feel like I'm going around in circles
Thanks

[#2]

That telephone number gets me Microsoft (in the US judging by the ring tone and accent of the automated message).
I would try the call again.
Regards

[#3]

Finally got through. No idea what was wrong with the number earlier today, but it's working now.
Activation sorted
Thanks