|"I average about 49k for the life until they start slowing down and making me attempt several tries for a dialtone at a decent speed."|
That's pretty good. You never actually get the full 56k speed.
You tend to get the most reliable connection and faster speeds from a "hardware" modem rather than a "sotware" modem ("winmodem"), but they're more expensive and harder to find new these days..
As in, a "hardware" modem has all that's needed built into it's board, it works in Dos, a "software" modem has fewer chips and requires software built into Win 95 and up operating system.
I have an old Zoom external 56K modem (serial) that is a hardware modem and it works fine. I only use it when someone insists I send them a fax, which hasn't happened for a few years.
You can buy anti-surge / anti-power spike devices that are just for the phone line.
Your problems may not be due to the modem.
(The following also applies to a DSL or ADSL high speed connection, except the max distance to the nearest phone exchange is a lot less.)
The farther away you are from the nearest phone exchange, the more electric and electronic noise that can get picked by the phone line, the lower the speed and the less reliable the connection is likely to be.
E.g. I have a friend who lives in the country - his 56k modem never gets a connection speed faster than 28.8k - the nearest phone exchange is in the nearest town, a long distance from his house..
The shorter the typical cheap flat phone cable between your modem and the wall socket is, the better, regarding picking up less noise where the modem is.
It's like an antenna regarding what it picks up..
Keep all the cheap flat phone cables that connect to the same phone line in your abode as far as you can from things that may generate noise - motors, florescent lights, unshielded speakers, AC cords, open computer cases, monitors, etc. - twice the distance- 1/4 the strength of what is picked up.
If it's a lot longer than 6 feet / 2 meters, you should run a standard twisted pair telephone cable (the same as is normally used between wall sockets) from connections behind the nearest wall socket ,and have a connection box on the other end you can connect a short flat cable to (use wires in the same twisted pair- a color,the same color with a stripe).
If you don't have standard twisted pair telephone cable between your wall sockets, if you can, run a twisted pair cable to where the telephone line enters your abode.
"New computer and cat5e wire to the jack. "
Same goes for the network cable. It has 4 twisted pairs of wires. If you're using that to connect to the nearest phone line wall connection, for the best result, to have it pick up the least noise, you must use a twisted pair in the cable - a color and the same color with a stripe.
Using a twisted pair cancels out most of the noise that would otherwise be picked up.