Disable SIP ALG on TG 4482 Modem

I have tried numerous times to go through tech support to find out how to turn off SIP ALG on this modem.  Tonight I was direct to Arris.  I thought this was funny since I rent this modem from Xfinity.  I also had this "2nd" level tech tell me to log into the router using 10.0.0.1, when the network is a 192.168.0.1 network.  It's a simple request, but NO tech support person knows how to do this, and they have dumbed down these modems for end users that we have no controls.  I have a VOIP device that wasn't having issues before I changed to this modem due to speed increase.  I had lots of control over my old modem, and now it's like you cannot do much of anything.  I just need to know how to turn off the SIP ALG to get my VOIP device working.  Please, if anyone can help, I would greatly appreciated it!!!! I rent this modem at almost $15.00 per month and pay lots per month for service.  If Xfinity cannot help resolve this issue, I may be considering a change in ISP's after 24 years.....