Inserting a <tab> into sed's replacement string

[bob parker <bob_parker@dodo.com.au>]

I'm using Woody with Gnu sed version 3.02 (the default).

I want to be able to insert tab chars into the output lines eg

sed = somefile | sed 'N;s/\n/\t/'

just gives me the literal 't' immediately following the number at the start 
of each line.

Attempting to actually type a tab key in the place of the '\t' in the 
replacement string just has the xterm barfing and I get the same result if I 
log on in a real terminal. So does attempting to insert Ctrl-I.

Is there some way of inserting the tab in octal or hex?

TIA
Bob Parker