Hi. How's the deduction of SMS Credits works? In my situation, I have a contact list in Zoho Campaign with a total of 1400 contacts but only 350 of them have a mobile number registered. If I select that contact list as my recipient in my SMS Campaign, how much SMS credits will be deducted? Are my SMS credits will be deducted for the worth of the 350 mobile numbers or the 1400 contacts? 

And another question about purchasing an SMS credit. Let's say I purchased a yearly 2500 SMS Credits, is that a recurring 2,500 per month in a year or just 2,500 for the whole year?