can't change steam phone number without old phone..

Contact support and wait 5 years to get an actual good answer

Not surprised at all...

Can't say I didn't see that coming. Not surprised at all...

You can ask your operator to give you a new card with the same number, while block the old one.

When you first installed the app you should have written down your R-code and generated a list of one time use Steam Guard codes.

I was just pondering this very question today myself....it's Valve's genius at play again.

The thing is, you used to be able to use one of the emergency Steam Guard codes to do it...but then they changed it to a numeric SMS code that only gets sent to the very phone you are trying to remove. Brilliance.

Same here
I contacted support and after a week i get my old number deleted, they ask you for proofs, in my case i gave them a lot of game keys and fiinally my old number was removed
Tbh steam support is really shitty compared to other companies, i had a problem with my hearthstone account once and the blizzard support was really amazing. To bad that steam is getting sillier every time

you cant log in into your steam account without the code? i have the mobile authenticator but it dosent require any code to log in my home PC.

Guesss your better option is to get your old number back, your mobile provider can help you with that.

there's that reset number when you sign up

Hump

no need to change steam phone number.

get a new phone, remove the old phone from your plan and put your phone number into the new phone.

are you using the "Steam-Mobile-Authentificator" on that stolen phone? You can unbind that phone with the R-Code you got when started the Steam-App the first time.

Help, I lost (or sold) my phone and can't log in! What do I do?
If possible, you should contact your wireless service provider and get a replacement phone with the same phone number. Steam will be able to send SMS messages to your replacement phone, and you will be able to recover your account as described below.
If you no longer have access to your phone and don't have your recovery code, you'll need the assistance of Steam Support. Use the "Contact Steam Support" button at the top right of this page to get help removing your authenticator. If you don’t have access to the email address that is currently associated with your Steam Account please provide proof of account ownership within your ticket.
source: https://support.steampowered.com/kb_article.php?ref=8625-WRAH-9030&l=english#sold

Like nonamebg suggested you should contact your operator and tell them your phone was stolen and that you want to deactivate your SIM. Also that you would want a new one with the same number. Then try deactivating steam guard with it.

I guess this is yet another reason to use Steam Desktop Authenticator over mobile one. You can't lose your PC and it's highly unlikely someone will steal it as they would have to break in your house.

When you authorised it you got a code in case of emergency, Should've written it somewhere in case of these things...

thank you everyone for the responses. I'm going to look through your advice and get this figured out. I'm going to close the discussion now. Thanks again