uploading data from R/3 to CRM

Hi Gurus,

We have the following scenario:

Our customer master data is created and maintained in R/3. Now we need to create and maintain in CRM.

1. we need to bring R/3 customer to crm and start maintaining only in crm

2. there should not be any number overlap

eg. 1000 customers in r/3 starting no. 1 to 1000, we need to bring this customer to crm and start maintaining in crm. then from cusotomer no. 1001 onwards need to create from crm.

Can anybody help me on the steps to be followed and the configuration settings to be maintained. How the number ranges have to be maintained and what settings should be done in CRM and R/3 before transfering the data.

Also the steps on how to upload data from R/3 to CRM??

Thanks.

Divya Gupta