Help why sms changes to mms when writing text

[qasmobi100]

Hi

can anyone please help me please, if i am writing a long text, it chages to mms why?
its doing my head in.

i have double checked the settings and cannot find anywhere where it would change it.

thanks in advance

 

[Slug]

if i am writing a long text, it chages to mms why?
its doing my head in.

A single SMS msg is restricted to 160 characters. Anything longer is sent as an MMS.