Can I use any other DECT 6.0 expansion handset?
I am unable to locate the EL50013 expansion handset. They are out of stock.
Will another brand or model sync with this system?
No. You MUST use the recommended handset. That'll be the same with any expandable system: it'll say on the box what model you need.
Don't expect to find any at Best Buy no matter your model.