For those who do not mess with this stuff much, you can easily send text messages to almost all cell phones for free using your email system.
The format is usually something like the following:
address <phonenumber 10 digit>@abc.xyz.txt
For example with my cell phone carrier I can send my cell phone a text message by composing an email as follows (with my phone number including area code in place of the 5555555555
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To: 5555555555@txt.att.net
subject: subject line of text msg
body text: stuff I want the user to read
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Common text from email addresses are listed on this web page.
http://www.emailtextmessages.com/ <--- list has not been updated recently so may have some old info, but many of these companies still use these addresses (mine does)
****** Test your particular cell phone so you know the proper paging address to have someone use. *****
It would be best to generate individual emails to each person.
If you put multiple user email addresses in a single email in the To: or the CC: field, the message header will essentially have a phone book of everyone's cell phone numbers.
Not everyone wants to share their cell phone number with the world.
You can accomplish this by putting all the email addresses to be used to send the text messages in the BCC address field (this hides the recipients from each other) the person only sees an email addressed to themselves not everyone else in the list.
Then you put some email address in the To: field for example your own email address or some alternate email address so you have a record of the pages sent.
For small groups like team members who already know each other's cell phone numbers, sending all the messages as CC: messages would not be a problem and one person with computer access could message the entire crew in a couple minutes for free from any computer that can send email.
If you don't know a persons cell phone carrier, most of the time you can look up their cell number on this web site and get the carrier name for free:
https://www.peoplesmart.com/All the SCTA or landracing.com or any other group would need to do is request paging addresses from folks that want to be paged with hot updates and build a file to be used to construct the mails.
Some email clients might have a limit on how many addresses can be in the BCC: field but that can be tested or verified with a phone call to tech support.
PS this is also a way to help you find your cell phone when you can't remember where you put it.
Send your self a text message that says "I'm over here dummy" and listen for the chime when the text message comes in (assuming the phone is on).