I just came across this service and I must be missing something...

they'll give you a free LOCAL pstn number, that anyone using a regular
PSTN phone can you from, and it will ring on your voicestick SIP
equipment, all for free!

They do have some paid services such as call forwarding, which Im
guessing means if the voicestick SIP equipment you are trying to reach,
doesnt answer or isnt on, it will automatically route it to a PSTN
phone.

Anyone have any experience with them?