I use a reg ans machine and it works just like it is plugged into a wall outlet...I think you are ok there...mine beeps when I have a new message just as it did when I had a reg land-line.
Your cordless phone system should work just as it would when connected to a land line.
HOWEVER, do NOT set up the voice mail system that is provided with this service. The Straight Talk Home Phone will provide a basic external voice mail feature which is provided by Verizon Wireless. It will be similar in features and function as if you had a Verizon Wireless cell phone where messages are kept on an external server and purged after a certain number of days.
Alternatively, you can set the answering device on your cordless phone to pick up on fewer rings than it would take to have the external voice mail system to activate (should you set up the voice mail provided by the Straight Talk Home Phone).
I have 8 cordless phones attached to my Home Phone box thru the base unit and it answers all calls first, so if we;re not on the phone, it will activate the cordless base's answering system, as normal.
However, if we're on the phone and a call comes in that we don't want to switch to at that moment (call waiting), the ST box will answer with its own answering system (if you set it up). One of the front blue LED's on the box will blink indicating that it has a call waiting for you to hear. Dial *86, enter your PIN # (done at setup), and it will deliver voice mails it has and allow you to save ot delete them.