when we use dialpad there is option on top to pick what type of call this is going to be.
but when we browse contacts all calls goes via gsm and there is no way to call using sip
OR i'm missing something here?

right now only way to make calls via sip is to duplicate phone number entry and have it not just as phone number but also as sip number.
considering that sip is use for telephony this is quite silly but i hope i'm just doing something wrong and someone is going to enlighten me

silly me, i worked it out
if someone else gets same puzzle just go to sip account and edit advanced options, there is spot you can select called "use for telephone numbers" (might not be exact wording but you can't miss it if you go to advanced settings)

You should be able to 'merge' the contacts if you created them separately.

I haven't got my phone back from Amazon so I can't check at the moment but I thought sure you can edit existing contacts and add in the SIP field for any contacts.

EDIT: you beat my post