Peer Details
Trunk Name: Gizmo5
disallow=all
allow=ulaw&alaw&ilbc
canreinvite=no
context=from-trunk
dtmfmode=rfc2833
fromdomain=proxy01.sipphone.com
fromuser=1747xxxxxxx <-- Your Gizmo5 number
host=proxy01.sipphone.com
insecure=very
secret=<password>
type=peer
username=1747xxxxxxx <-- Your Gizmo5 number

User Details
(not used)

Register String:
1747xxxxxxx:<password>@proxy01.sipphone.com

Notes:
If you are using Gizmo5 to get free outgoing calls to U.S. cell phones, etc. via their Backdoor Dialing then you may want to prepend the 0101 code using the dial plan, depending on how you set this up. For example, if you have set up an outbound route that routes calls to certain specific cell phone numbers in the 212 area code to this trunk, then in the trunk dial rules you may want to add something like this:

010+1212XXXXXXX
0101+212XXXXXXX

Or, if you are careful about the traffic you send to this trunk (so that all numbers are pre-validated, or Gizmo5 numbers) then you could use something more generic:

1747XXXXXXX
1+747XXXXXXX
010+1XXXXXXXXXX
0101+XXXXXXXXXX

(747 is the pseudo-area code that Gizmo5 uses, so you don't want to preface that with 0101, therefore put it first so it will match and not fall through to the 0101's).

Note that there is a very short recorded message played at the start of each "free" call, and also note that (at the present time) Caller ID info is not passed through, but instead it will send a Caller ID number in the 262 area code, so you might only want to use this for free calls to friends and family members (in theory this number can be used by the person you called to return your call, but only if they call back from the number you called!). Another "gotcha" is that if your call out credit balance ever goes to zero or negative, "Backdoor Dialing" appears to stop working properly (even though those are "free" calls) - it will ring the called party's phone, but the moment they answer it will disconnect (hopefully this will be fixed someday).

It appears that wherever the 1747xxxxxxx number is given in the above configuration, it is acceptable to substitute the account username (but be consistent, use either the number or the username, but not both).

Some users have reported that when sent from Asterisk, passwords are case sensitive. If you have problems, go to the Gizmo5 login and say you have lost your password an get them to e-mail it to you, then copy and paste from the e-mail into your configuration. Note that passwords are NOT case-sensitive when used with the softphone, Gizmo5 web site, etc.

If you always get an "all circuits busy" when trying to place an 0101 prefix call, check your fromuser and fromdomain lines to make sure they are present and correctly formatted.