Here’s my dilemma. I don’t know of a service that does call forwarding (remote or otherwise) for a flat fee. When forwarding calls from one number to another, there are actually two legs to the call. The inbound call to your 404 number for example, and also an outbound call to your 770 number for example.
Generally, for service providers outbound calls tend to be more expensive than inbound calls, so while inbound calls are often available for flat fees, outbound calls not so much.
To try and keep this as simple as possible, I think VoIPO might be a good choice. Their charge is $3 per month for the number if paid annually or $5 per month if paid monthly. That gets you 500 inbound minutes (the calls coming into your 404 number. Outbound calls (for the forwarding to your 770 number) are metered at a penny per minute. If those 500 inbound minutes (a little over 8 hours) are sufficient the corresponding charge for 500 outbound minutes would be $5. So, if a bit over 8 hours of call volume is sufficient, you can do what you’ve been doing with Talk America with VoIPO for $8 to $10 per month.
Another option is Google Voice but it’s a hassle to move a landline number to Google Voice. That said, once there, Google Voice was built for call forwarding and would be free. When I say getting a landline number to Google Voice is a hassle, have a look here to see what I mean: Transferring a Republic Number to a Service Provider That Refuses Landlines. I wrote the article for folks wanting to move their Republic number to a service (like Google Voice) that doesn’t accept landlines but the process applies to any landline number.
Finally, I’d be remiss if I didn’t at least mention Republic’s Extend Home adapter. This, however, wouldn’t be a remote call forwarding solution. Instead, you’d move the 404 number to Republic (which would require a second Republic cell phone) and use the adapter to receive calls to your 404 number directly without forwarding them to your Comcast number. More on Extend Home is linked here: Frequently Asked Questions (FAQ) for the Extend Home Adapter.
As you can see, there are multiple options available to you, however, all get technical.