question

I have an incoming call to my extension every day from a telemarketer. I've blocked the number both at my extension and on the main line (I am the administrator) but it still comes through. I'm wondering if the caller ID info is somehow causing it to mismatch the number. On my phone and in the call log the ID shows up as 1610XXXXXXX but the blocked number system removes the 1 and makes it 610XXXXXXX. That should match the number but it appears that it does not. This is driving me nuts and any help would be appreciated. Thanks