Hi Zhigang, > According to 23.040: > The maximum length of an uncompressed concatenated short message is 39015 > (255*153) default alphabet characters, 34170 (255*134) octets or 17085 > (255*67) UCS2 characters.
The structure of UD when concatentation is used is like this: [UDH length][IEI1][IEI1LEN][IEI1DATA]PAYLOAD One can use two header types for concatenation. 16 bit sequence and 8 bit sequence. 16 Bit sequence uses 4 bytes while 8 bit sequence uses 3 bytes. So the total overhead is: 1 byte for udhl + 1 byte for iei + 1 byte for length + 3|4 bytes = 7 for 16 bit header and 6 bytes for 8 bit header. So the you provide above numbers are correct for the 8bit case, but not correct for 16 bit case. In 16 bit case we can encode 255 * 152 GSM characters and 255 * 66 UCS2 characters (the UCS2 characters cannot be split in the middle). > > But in oFono didn't match above: > For UCS2 is (255 * 66), default alphabet is (253* 153) oFono uses 16 bit sequence by default, so at least in the case of UCS2 it is correct. For 7bit case you need to limit the payload to 255 * 152 characters. 253*153 will in fact result in 255 segments when using 16 bit headers. Regards, -Denis _______________________________________________ ofono mailing list email@example.com http://lists.ofono.org/listinfo/ofono