I'm looking at setting up an iTalk account to use for international calls only.
From what I've read, most ATA's default to VoIP and only make an outbound call via PTSN if a code is dialed or the VoIP network is done.
I'm looking for recommendations for an ATA that can be configured to default to PTSN and only use VoIP if a code is dialed.
I don't want to spend too much money, so the following 3 seem like my best options (cheapest first):
1) Grandstream HT-486 (~$54 including shipping from trademe)
2) Linksys AG310 (~$90)
3) Dynalink/Netcomm V300 ($90 for a 'MyNetFone' setup one, is this locked? (and can it be unlocked?))
4) Linksys SPA2102 ($109 on a 12 month contract through slingshot, and we're on a 12 month contract anyway for TNBT, are these locked (and can they be unlocked?))
If anyone can advise me as to which of those have the above functionality, or suggest any other low-cost options that'd be appreciated, as would any other relevant advice.
I'd also like confirmation that these can work from behind a NAT and don't require any port forwarding (if not, I'd like information on what they do require).
EDIT: Doing a bit more research into VoIP, and it seems I can use any international provider, not necessarily a NZ provider. Does anyone have experience with this that can comment on the quality of service, or can suggest a provider with cheap rates to Germany?
SECOND EDIT: Added the 4th option and costs of all 4.