403 Forbidden on ITSP outbound call

[Paul Cobley]

Hi,

This is a new install of CUCM9.1 with SIP trunks on a CUBE (Version 15.2(4)M2). The CUBE is behind an ASA and a PIX. The ASA is the corporate perimeter and the PIX is the client site.

Outbound I get a 403 forbidden then fast busy. We are sending the call setup to the ITSP fine.

Inbound the call rings my extension but when I answer the PSTN still hears ringing, I hear dead air - so I think the response to the invite is not being sent to the ITSP.

I have my concerns that this is down to the ASA/PIX config but would appreciate a sanity check.

I've attached a "debug ccapi mess" & "debug voice ccapi inout"

thanks

PC.

[Ayodeji Okanlawon · Accepted solution]

Paul,

Looking at the debug..the cause code is "Cause Value=57" This refers to a bearer capabilities issue. From your INVITE you are not offering any media capabilites to the ITSP..

I suggest you enable early offer on either the globall level or on your dial-peers facing ITSP

voice service voip

sip

early-offer forced

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

[Paul Cobley]

As always with SIP, you hit the nail on the head.

The issue was resolved by adding the "early-offer forced" but also by the customers security team sorting out a double NAT - the ITSP trunk negotiates an ASA and then a PIX so there were some fixup & inspect issues involved also.

Thanks for taking the time to assist

[Ayodeji Okanlawon]

Glad to help and thanks for rating and compliments

Please rate all useful posts

"opportunity is a haughty goddess who waste no time with those who are unprepared"