Hi Aishwarya,
You are right, you cannot use SAP GUI transactions based on transaction launcher in SAP CRM ABAP 7.0 EHP 1. The prerequisite to use sap gui is that your CRM system should be either 7.0 EhP2 or higher release. For the backend clients (ERP), the Suite Foundation Layer 7.02 or higher is required. This means ERP EhP5 or higher release. You can refer to SAP Note 1890755 for detailed information.
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Note 1890755
https://launchpad.support.sap.com/#/notes/1890755
So you need to create a WEBGUI based BOR transaction launcher to call ECC tcode from CRM. You can find link "Almost Everything About Transaction Launcher" in KBA 1877395, please open and view the document from this link and follow the same to set up your BOR transaction launcher.
KBA 1877395
https://launchpad.support.sap.com/#/notes/1877395
Best Regards,
Bruce