little syntax mistake, try this
<div><br></div><div><span class="Apple-style-span" style="font-family: arial, sans-serif; font-size: 13px; border-collapse: collapse; "><div>exten =&gt; s,1,Dial(SIP/Ext400&amp;Local/${EXTEN}@home-context)</div><div><br>
</div><div>[home-context]</div><div>exten =&gt; s,1,Set(CALLERID(num)=<span style="font-family: Arial; border-collapse: collapse; ">44112233445566)</span></div><div><font face="Arial"><span style="border-collapse: collapse; ">exten =&gt; s,n,Dial(SIP/TheWorld/441234567890)</span></font></div>
</span></div>