How to send a notification to a user at specified time (between 9am to 10 am) daily? I have created a form which contains a CCK field "send sms" (checkbox) with two options:


Send sms between 9am to 10am  (= option 1)
Or anytime (= option 2)


If the user selects option 1, then notification should send between time 9am to 10am to user.

If the user selects  option 2, then notification should send at any time.

How to achieve this functionality?
Part 1: Rules

Have a look at my answer to "Rule to store user&#39;s last post date and scheduled rule based 30 day reminder", a question that is a variation of part of your question. It explains how you can use the Rules module for this (using the Rules Scheduler also).

Part 2: Message Stack

Have a look at the Message Stack, these are the basic components and dependencies of it:



Some more details about the Message-related modules (=quotes are from the module's project page):


Message:


  The Message module is the core of the message stack. It enables logging and displaying system events in a number of different use cases. Events that are recorded over time are sometimes call activity streams. Exportable messages subtypes can be created for different use cases with custom fields and display (view) modes.

Message Notify.


  This module provides a method for sending a message via a notifier plugin. Message Notify comes with plugins for email and SMS and may be extended to other transport mechanisms as required.

Message Subscribe.


  With this module, users who subscribe to content will be notified when events occur that involve that content. The module leverages the Flag module, which provides a subscribe functionality to users.



Quite a few popular Drupal distributions already adopted to this Message Stack, Open Atrium is one of them.