I keep getting "The following phone number is too long:..." "maximum SMS recipient is 11 digits,..."
*** Error on new SMS only, reply on existing threads work fine. ***
I understand this but I am trying 10 digit number. First I thought it was because I had () around area code but after deleting them it still gives same error. Uses of (xxx)xxx-xxxx; xxx-xxx-xxxx; xxxxxxxxxx All give same error. (Samsung Note 4 Android Lollipop, browser plugin in Chrome doesnt give me option to SMS just states they are not a Hangouts user when I try to message.)
Hangouts is my default messaging app. Google Voice account and Gmail same user name/account. I am still able to SMS my old contacts.
Not an exact problem as you have noticed, but may be related: the web hangouts version cannot send sms on a wifi only device. I tested this using my cell phone (works), LTE tablet (works), and laptop/tablet combo (does not work). I'm going out on a limb guessing that Google is cutting back on the capabilities of Hangouts going forward unless you opt for the paid version (businesses).
I have only skimmed some info about the re-purposing of Hangouts-- but it occurred to me that the juxtaposition of "hangouts" and "business" is jarring.