Cisco IP Phones and SD-WAN

[ttydev]

Our Cisco IP Phones (7965) are unable to download firmware from CUCM.  During the boot process, the phones error out with "error", and continue to loop.  Apparently, this started to occur after we added an SD-WAN appliance (which replaced the location's router).  The former router handled DHCP requests, where now, the SD-WAN appliance does.  All of the phones in question are assigned an IP (correct DHCP subnet), and are pingable, however, GUIs cannot be reached.  For troubleshooting, we took one of the devices to a different site, and it functioned as intended.

Evidently, this appears to point to the appliance, however, the vendor is not taking ownership of this.

Thanks in advance for any insight.

[Jaime Valencia]

I don't think there's anything specific regarding Cisco UC and SD WAN, quick Google search shows it should work.

https://www.cisco.com/c/en/us/solutions/collateral/enterprise-networks/sd-wan/solution-overview-c22-744788.html

In the end, it doesn't matter what you use, or what brand you use, the phones need to have connectivity to the backend servers for signaling, and between each other for media. There's documentation regarding ports required for devices to work, I'd start by making sure all the necessary ports are open.

But, this does seem to hint the SD WAN configuration to be the culprit and as such, should be owned by whoever you're paying for to deploy it. 

[Nithin Eluvathingal]

You mentioned phones got the IP address, a small doubt does option 150 configured on the DHCP pool ?

Does the phones have right TFTP address ?

As JAVA mentioned, refer the Port guide. You can access the TCP and UDP Port Usage for CUCM version 12 from below link.

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/12_0_1/systemConfig/cucm_b_system-configuration-guide-1201/cucm_b_system-configuration-guide-1201_chapter_01010110.html

[TONY SMITH]

Try manually configuring the correct TFTP address on a phone at the problem site.  If that doesn't help, then manually configure all IP parameters.  That will tell you whether the problem is the SD-WAN itself, or whether it's a DHCP issue.

[ttydev]

This issue was resolved by correcting the formatting of the vendor class ID.