Yes, it's easy. You have to ask Twilio customer support to enable 'Alphanumeric Sender ID' in your project. Here's the link for that. Once that's done then all you need to do is to set the 'From=' in Administer/Settings/SMS Providers to whatever you want. Of course, users cannot then reply or 'STOP' etc. But it works and there's nothing to enter or ...
I suspect the unicode issue arises from the clickatell extension. It uses the utf8_decode() function to decode the message text from a UTF-8 string to ISO-8859-1 before posting to Clickatell. Hence Clickatell manages UTF-8 messages, the use of utf8_decode() is not necessary, and removing it resolves my issue above.
Replace original code:
As per Clickatell api documentation the api url to send sms is
Please cross check in clickatell the api key under SMS Integration tab(it should be of 24 chars with '==' at the end).
As mentioned in my comment to Demerit's answer I successfully achieved my objective to send a QR code to an event participant's phone (albeit the URL and not the image).
I installed the Clickatell extension for CiviSMS and the QR Code Checkin extension to generate the emails or SMSs to send the QR Code or its URL to event participants.
The instructions to ...
Looks like sites/all/modules/civicrm/CRM/Activity/BAO/Activity.php is failing in function function sendSMSMessage( because $doNotSms = TRUE; on line 3154. Set it to false and you should be Ok. However, the check will not happen, so all numbers (even Do Not SMS #s) will get the SMS.
The other option is to comment out the following block and add an if block:
It doesn't look like the Twilio extension supports MMS at the moment and probably not Clickatell either but you can text the recipient the link to the QR code. It looks like you would need a public link anyway for Twilio's api if the extension supported it.