We have been developing some plugins for group messaging using the "Send Response to URL" function in keywords.
Rebroadcasting
Rebroadcasting is sending a text message to a longcode that sends to a list in your account.
Use the following URL directly on the Inbound Options for your virtual number.
Use your API key and secret located in the API section of your account in the following URL.
Create a list and get the list ID. The list ID can be found in the list name when you are viewing your list.
http://www.transmitsms.com/plugins/rebroadcast.php?apikey=xxxxxxxxxxxxxxxxxxxxxxxxxxx&apisecret=xxxxxx&list_id=xxxxxx&caller_id=614xxxxxxxx&allow=614xxxxxxxx,614xxxxxxxx
You can set the caller ID in the URL to any static mobile number and all responses will be sent to it. If you set the caller ID to a name, people cannot respond.
You can also override the caller ID to be the allowed senders number by removing the &caller_id=614xxxxxxxx parameter from the URL completely.
Once this is setup, texting your keyword then a space then your message to the longcode, the message will be sent to everyone on the list.
Set the allow parameter to limit who can trigger the send.
To set rebroadcasting to work on a virtual number directly without a keyword, use the following URL.
http://www.transmitsms.com/plugins/rebroadcast-wildcard.php?apikey=xxxxxxxxxxxxxxxxxxxxxxxxxxx&apisecret=xxxxxx&list_id=xxxxxx&caller_id=614xxxxxxxx&allow=614xxxxxxxx,614xxxxxxxxGroup Messaging
With our group messaging plugin, everyone on the list that texts the number will receive the message. Also they will be identified by their [firstname] and [lastname] variables. If they aren't populated the last 5 digits of their number will identify them in the message.
http://www.transmitsms.com/plugins/groupchat.php?apikey=xxxxxxxxxxxxxxxxxxxxxxxxxxx&apisecret=xxxxxx&list_id=xxxxxx&caller_id=614xxxxxxxx&longcode=614xxxxxxxx&keyword=no&autoadd=no
If you want to use a keyword to trigger set the parameter keyword=yes in the URL and put the keyword in your setup.
If you don't want a keyword add the URL directly to inbound options on your number and put keyword=no in the parameter.
Make sure your longcode parameter is your dedicated virtual number.
People can opt-in just by texting the number and can stop receiving messages by texting STOP.
The person can edit their name by texting NAME <firstname> <lastname> to the number.