SBG6580 modem/router

Trying to use an office issued Polycom VVX300 phone at home (Windows 7 PC). Setup keeps resulting in error message that the line is unregistered. 8x8 tech support says some settings on my Motorola SBG6580 modem/router need to be configured as follows: 1: Disable All of the Following • SIP Normalization • SPI (or set to Pass Thru) • DOS • SIP/VOIP ALG 2: Configure these Ports with High Priority • UDP 30000-30040 (source port range for VOD aac) • UDP 5196-5199 (SIP signaling) • UDP 3478-3480 (STUN) • UDP 2222-2269 (Polycom media) • UDP 16384-16404 (Linksys media) I've done the port configurations but still getting unregistered line message. I've read that SIP/VOIP ALG cannot be disabled on my modem/router? Is there a workaround? Any assistance will be appreciated.