how to change the textbox's format as phone number

hello , in the winform I want to make the textbox's formats as phone number , while I type for example 55555555 it will will appear as 55 555 555 .... I tried in the text_changed event to make the format as string.format ( "{0:#, ## ### ###}", convert.toint (textbox.text) ) but it didn't work , the cursor keeps changing its place while I type