At present, SMSes in OpenVPMS are limited to 160 characters.
There is also an assumption that all messages will be encoded using the 7-bit GSM character set, allowing 160 characters per message
To better support automated appointment and reminder SMSes which often exceed 160 characters, multi-part (or concatenated) SMSes are required.
The maximum number of supported parts will be configured on the entity.SMSConfigEmail* archetypes, and default to 1.
The maximum length of a message will be calculated by first determining the message encoding (GSM or unicode).
For GSM messages:
single messages have a maximum length of 160 characters. Some characters are encoded using two bytes.
multi-part messages have a maximum length of 153 characters per part
For Unicode messages:
single messages have a maximum length of 70 characters.
multi-part messages have a maximum length of 67 characters per part
NOTE: the SMS editor will not be changed to support unicode/escaped GSM characters as part of this JIRA. See
http://unicode.org/Public/MAPPINGS/ETSI/GSM0338.TXT for details on the GSM encoding
https://www.clickatell.com/articles/technology/the-uncomplicated-guide-to-concatenated-sms/ for an overview of multi-part messages