You should have a premium Workplace Account and then go to the Admin Panel

Enter the people section in the left side then “Add Person“

Add the email and phone number of the victim

we have added a new user and status should be“invited” so choose the “three point” and send a claim notification option

choose “Send claim notification “

Then choose “ All unclaimed accounts “

This is to send an email instruction but wehave to do some trick to send an SMS instead ofemail (SMSoption is not showing in the UI ).Type anything in the message(this message will  noti ncluded in our SMS)then Intercept the request and tap “send button

change the value SMS to TRUE,this is to tell the server to send anSMSto the phone number of the victim

POST /atwork/async/send_confirmation_all/?dpr=1.5 HTTP/1.1Host: workplace.facebook.comConnection: closeContent-Length: 576

email_custom_text=anything&email=false&sms=true&unclaimed_within_department&unclaimed_for_manager&users_to_send&__user=100028254561229&__a=1&__dyn=5V8WXxa-cxp2u6aJei9FxqewRyWzEsheC267Uqzob4q6oF1q13wFw_x-ewSxumeK7EiwhUlwxz8S2S4okw-Dwxxu1PyoiyEqx60xU5SF82Nxi13wDw-CK6ooxu3a1lwRyUvy88E6W78jG48423648y4Ehyo8K2y6-3CcGEbo8lCwo87e7ouzHAye1iyEiwTxe3-2i&__req=cp&__be=1&__pc=PHASED%3ADEFAULT&__rev=4282274&fb_dtsg=AQGyUiM0WegT%3AAQEhjeNz_z9i&jazoest=2658171121851057748871011038458658169104106101781229512257105&__cid=262318221066636&__spin_r=4282274&__spin_b=trunk&__spin_t=1536195578

The result: a messageis received fromFacebook with this form

[company name ] has set up workplace for you

What if we change the company name to our message?

Going back to the Admin Panel,and go the “preferences“, I Noticed that we are able to put a strange company name with more than 30 characters ( including a link ) so we can type a good message in the company name so we will use the“company name”as our message :D note that no limits for how many times we change the “ company name “ 

I type this message including the name of my website,then save the company name

Now re-send an SMS message ( same steps mentioned above)

Another Example :) Click on show image