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Vijay S
New Member
May 30, 2026
Question

SIP ALG and voip with ecrypted sip traffic on port 8934

  • May 30, 2026
  • 3 replies
  • 50 views

Hi guys,

anyone had any experience with cisco webex calling and fortigate. basically SIP traffic are encrypted and sent over tcp 8934 via fortigate to internet (webex).  we have been experiencing, one way audio, transfer fails, unable to hold and resume , drop calls (all intermittent).  These usually points to SIP ALG issue but it is disabled.

am I missing anything on firewall?  any other way to double confirm if those packets are dropped due to alg?

 

i would really appreciate some insights pls.

3 replies

sjoshi
Staff
sjoshi
Staff
May 30, 2026

Hi ​@Vijay S ,

 

Refer this article and see if SIP has been completely disabled.

 

Thanks, Salon
Toshi_Esumi
SuperUser
Toshi_Esumi
SuperUser
May 31, 2026

Since I don’t have any experience before with Cisco webex, what I would do in that situation is to exempt the specific traffic from deep-inspection, certificate-inspection and all UTM features especially IPS by using “Cisco-webex” internet service.
If traffic is matching the exempting policy but still having the same SIP related problem, I would call in TAC for help.

Toshi

AEK
SuperUser
AEK
SuperUser
May 31, 2026

Hi Vijay

Cisco recommends to disable SIP ALG.

https://help.webex.com/article/b2exve/Port-Reference-Information-for-Cisco-Webex-Calling

 

AEK
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