Step 1: Login to your grandstream admin interface. The default login username and password for grandstream 6102 is admin/admin.
Step 2: Go to VOIP trunks-> create new SIP trunk.
Step 3: Configure New SIP Trunk. PS: Type should be register SIP Trunk. Get the Hostname, Username and Password from the email you receive when you created a new SIP Account.
Step 4: Click on Save. Go back to Status and find the status as registered green.
Step 5: Go to Outbound Routes. Enter the rule name, pattern as "_ZXXXXXXXXXX" and select the trunk which you have created. Check the image below for better view
Step 6: For routing your inbound call coming on your DID number, go to Inbound routes and Add the DID number as "_123456789" under pattern. Route the calls to your desired destination.
Step 5: Check the Registration at DIDForSale. Portal. Account Portal -> Interconnection -> SIP Account. Notice the green light in front of the SIP account you used to configure IP PBX.
Step 6: Now you should be able to make and receive phone calls. To receive phone call, you need to configure the phone numbers in your DIDForSale Account Portal.