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403
4xx Client error, RFC 3261

SIP 403 Forbidden

SIP 403 Forbidden means the server understood your request and refuses it. Your login works, but this call, number or address is not allowed.

Who sends it
The SIP trunk
When
Placing the call (INVITE)
Retry?
Not until the cause is fixed. Retrying the same call gets the same answer.
The caller hears
A fast busy tone or a short failure message straight away, without ringing.
PBXYour phone or PBX
SIPThe SIP trunksends 403
☎The called side
FIX

What causes 403, and how to fix it

403 means the server knows who you are, or does not care, and still says no. On a SIP trunk it is usually a policy decision: the destination, the source address, the account state or the caller ID.

  1. 1
    Most common

    The number is one your login may not call, such as a premium-rate or special number.

    Look up the number in the rate finder. Premium-rate and special numbers are blocked by default to protect you from toll fraud.

  2. 2
    Most common

    On a prepaid trunk, the balance does not cover the call. Depending on the provider this shows as 403 or 402.

    Check your balance and add credit, then try again.

  3. 3
    Sometimes

    The caller ID you send is not allowed on that route.

    Send a number you own, such as your virtual number, or leave the caller ID to the trunk default.

  4. 4
    Sometimes

    Calls arrive from an address or with credentials the trunk will not accept for calling.

    Make sure the PBX sends calls through the registered login, with the same username and server as the registration.

  5. 5
    Rare

    Too many failed attempts got your address blocked for a while.

    Stop automatic retries, fix the cause, then wait before calling again.

LOG

What 403 looks like in a SIP log

SIP/2.0 403 Forbidden

Capturing one: reading the SIP log.

SIP response
SIP/2.0 403 Forbidden
Via: SIP/2.0/UDP 203.0.113.10:5060;branch=z9hG4bK-74bf9
Call-ID: [email protected]
≠

Not to be confused with

403, 401, 404 or 603?

401

Unauthorized

The server needs your credentials. 403 means it has them and still says no.

404

Not Found

The number does not exist. 403 means it may exist but you may not call it.

603

Decline

The person or their network declined. 403 is the trunk refusing before the call leaves.

FAQ

SIP 403 questions

Does SIP 403 mean my password is wrong?
Usually not. A wrong password shows as repeated 401 or 407 responses. 403 means the server knows who you are and refuses the request.
Why do only some numbers give 403?
Usually because those numbers are blocked for your login, such as premium-rate or special numbers, or because the caller ID is not accepted on that route. Other numbers work because nothing blocks them.

Not 403? Look up another code.

The full list: SIP response codes. 403 again and again? Check your SIP trunk configuration.

All SIP codesFind a fault by symptom