I'm having trouble adding the parameter user=phone in the RURI. I have tried to use the function add_uri_param from siputils module but it doesn't work (see below). Here is the code I use to add user=phone parameter to FROM, TO and RURI

uac_replace_from("", "sip:$var(normalized_number)@sip.domain.com;user=phone");
uac_replace_to("", "sip:$var(normalized_number)@sip.domain.com;user=phone");

$rU = $var(normalized_number);
add_uri_param("user=phone");

Thanks in advance for any hints,

Best regards,

Minh Phan