The Vodafone customer care number for seeking support through its 24x7 helpline number (no) is 111. However they do have state specific alternate numbers on which one needs to call in case one is roaming out of their home circle. You can check all toll free no here for varying services.
Like Vodafone Kolkata Customer care number for roaming users is 9830098300 and Punjab roaming guys can dial 9888098880 to speak to their home circle roaming customer care. This is a draw back with Vodafone that the same 111 number does not help you while you are on roaming as they access numbers region vise and not on All India basis.
Thus as a thumb rule always speak to cust care before you roam and store that number with you and remember that these numbers which are mobile numbers helplines are chargeable numbers.