Hey guys so simple "Verizon home phone connect" work's great for my sc1200...only $20/month unlimite call..
I am using NetTalk. Plugs directly into my router, $30 a year. Every once in a while, I'll either dial in to the SC1200, or manually trip the alarm, just to test the dialing function. So far, no problems.
Only issue with these two options and VOIP is that if they cut the power your SC1200 is not going to dial out.
Same if they cut the phone line again your SC1200 is not going to dial out.
Now going the cellphone route you don't have these issues (no power, no phone line). The xlink box does need power and to solve that issue if you get a UPS box you can have the xlink box use the batery backup in case the power goes out so you can still get the phone call and/or call the SC1200 as well.