Purchasing my own gateway

Hello,

I am wondering if it would work if I purchased my own gateway instead of using the one furnished by comcast for $11 a month.  I only use the gateway for phone service since I have my own router and modem.   I realize that it must be compatible with Xfinity, but is there anything else I should look for?  It should be a simple call to activate the device on my existing account/Xfinity phone number, correct?   Im looking at a T6862G/CT from a retailer.  Please let me know if there may be any issues.