I'm a bit confused on how to use Call Parking with a Grandstream phone. Specifically I have a GXP2010. I've programmed 4 of the buttons for SP0, SP1, SP3, and SP4. I can park a call by pressing "Transfer * 0 0". That works fine. I can pick the call back up by coming 'off hook', and then pressing "Transfer * 1 0 Send". That works fine. I can pick the call back up by coming off hook, and then pressing "Transfer * 1 0" and then waiting for the 'dial timer' to expire (set to 3 seconds). What I can't figure out is how to use the SP0, SP1, etc. functions and the keys that are programmed for those. If I press one of these keys, a line is taken 'off hook', and I hear music. But none of these seem to work to be able to either park a call or pick a call back up that has been parked. How do I use these functions? John Rayfield, Jr.