they call me at least once a day and never leave a voicemail...do u know who it is?

That would be a call from Amnesty International. They are fundraising, and will not leave you alone until you commit to increasing your monthly contribution by eg. $10 or $20 a month for this, that, or the other cause.
I am a firm believer in human rights and I support AI, but I disagree with their tactics of fundraising. It is intrusive to telephone someone repeatedly until they finally give in and answer the bloody 'phone. It is sheer manipulation to appeal to their compassion for humanity by detailing whatever human rights abuse issues are current and NOT GIVE UP until they have squeezed more money out of them.
Decide how you want to handle it, but don't be afraid to pull the plug, hang up, etc. Don't be 'guilted' into contributing more just because you're a kind and compassionate person.

I have received repeated missed calls from this number.There is no voicemail message, and when I rang the number back, there was only a message and I couldn't understand the name. The message did not help.

I've been getting calls from this number everyday for ages now. I'm guessing no one knows who it is.......

I have received repeated missed calls from this number.
There is no voicemail message, and when I rang the number back, there was only a message and I couldn't understand the name. The message did not help.

Got a call from this number at almost 8pm! Aren't there rules about that shizz?