I can see the appeal in letting GV handling your POTS filtering and e-mail.
I think the forwarding you are doing is always going to have a delay.
An alternate (but more difficult to set up) approach would be to:
- add a virtual number to your CenturyLink (CTL) POTS account
- (after that number is working, you might need to make it the primary number on your CTL account)
- remove old POTS number and add the new virtual number to the GV account
- port your old POTS number to GV (a multi-step process) as a partial port from CTL
now your new number isthe POTS number, and the old number rings direct to GV without the forwarding delay.
Personally I would NOT do this. I don't trust GV with my POTS number. Last week I initiated the process to port my POTS number from CTL to Anveo.
sdb
P.S. To port a landline number from centurylink into google voice requires you first port the number to a mobile carrier, e.g. tracphone, t-mobile pay-as-you-go, AT&T go-phone, etc. That phone will cost $10-20 and usually the port is free. Then mobile into GV is possible, but it does have the risk that GV may not be able to do the port even after all that.