The 57i is a four line SIP phone and you only have one phone, so the easiest thing to do is to forget the ring group and set up as follows:
- Order all your DIDs from VOIP.ms
- Create two subaccounts with unique usernames and password. On the bottom portion of this screen you can set up local extension numbers.
- Set up your 57i such each line logs into a different subaccount
- Under Manage DID on the portal, set the each routing to a sub account
This way, each DID show up as a different line number on the 57i. This is generally
preferable to having the two DIDs pointing to the same main account because you will now have visibility over which line is call is coming from as well as being able to control which line you are calling out on.