SMS
The amount of data that can fit into a single SMS segment is limited -- typically 160 bytes, or 160 basic characters. So 1 SMS segment = a 160 bytes message = a 160-basic text-character message.
1. What happens if you exceed 160 basic text characters in a message?
In this case, you are charged for additional SMS segments. Here’s how SMS segments are broken down:
1-160 character(s) = 1 SMS segment
161-306 characters = 2 SMS segments
After you've reached 306 characters, every 153 characters would count as an additional SMS segment (ie 307-460 characters = 3 SMS segments)
2. What happens if you use emojis or special characters in your SMS message?
Emojis and special characters use more bytes than basic text characters so when you use them in an SMS message, the number of total characters you can use in SMS segments changes. If at least 1 Emoji or Special Character is used in an SMS message, the total SMS segment character count (basic text characters + emojis + special characters) is as follows:
1-70 character(s) = 1 SMS segment
71-134 characters = 2 SMS segments
After you've reached 134 characters, every 67 characters would count as an additional SMS segment (ie 135-202 characters = 3 SMS segments)
3. What do the recipients see when they receive SMS messages that are over the single message character limit and are counted as 2+ SMS segments?
Each carrier handles these types of messages differently. Here are examples of known carriers:
Recipients with an AT&T or Verizon service will see the message as one long SMS message.
Recipients with other carriers may see messages like these split into multiple segments. The delivery order of the split segments can’t be guaranteed, so sending messages that fit within a single segment is recommended.
MMS
The amount of data that can fit in a single MMS is limited to .5 mb. Within the .5 mb limit, you can send up to 10 files (with a .5 mb limit per file) and 1,600 characters per MMS.
4. What happens if you go over the .5 mb limit?
Each file would be converted to an URL and sent as separate SMS segments. Additionally, the character message associated with the original MMS message would be now sent as an SMS message.
10 files + 1,600 characters <.5mb limit = 10 SMS messages (10 file URLs) + 1,600 character SMS message (11 SMS messages).
5. What happens if you exceed the .5 mb limit per file?
The uploaded file(s) over the .5mb limit would be converted to a URL and sent as a separate SMS message.
1 file <.5 mb/file + 2 files >.5 mb/file + 1,600 characters = 1 MMS message + 2 SMS messages (2 file URLS).
6. What happens if you go over the 10 file limit?
Each file would be converted to a URL and sent as separate SMS messages. Additionally, the character message associated with the original MMS would be now sent as an SMS message.
11 files + 1,600 characters = 11 SMS messages (11 file URLs) + 1,600 character SMS message (11 SMS messages).