It doesn't appear dead to me, based on your comments.
Which VoIP service provider are you using?
Two things you apparently haven't tried:
Delete and then re-configure SP1 and SP2 on the OBiTALK web portal, but this time, swap the SIP username and password for SP1 with the SIP username and password for SP2 (provision the number you were using on SP1 this time on SP2, and vice-versa for SP2). Don't change anything on your telephone. Now, what happens? Did the symptom stay with the telephone number (username/PW)?
Many VoIP service providers won't let you configure the same credentials (SIP username/PW) on more than one user agent (ATA or softphone client) at the same time. One client will grab control of the registration and prevent the other from ringing. Disable the softphone client and test again.