Need Recommendations to connect 8 Remote sites via dial up

Need Recommendations to connect 8 Remote sites simultaneously via dial up to our 2003 server which sits behind a Cisco 2600 router. What is the easiest,least expensive and most secure way to to connect 8 remote site via dialup? Can you please provide me with white paper links with a step by step setup instructions, please. THanks in advance for your help and assistance if this is the wrong group could you please provide me with link to the correct one. I am a member of Technet Plus just dont have my login code here at home