Why running SIP on Cisco 7900 Series IP Phones is so overrated…

The Cisco 7900 Series VOIP phones. It has literally defined a generation of enterprise telephony. You hear a lot of about Cisco VOIP phones capable of running anything off the Cisco world; such as supporting Session Initiation Protocol (what I like to call Tip and Ring over IP or TROIP.)

I personally think this is overrated. First off, Cisco did early on support three different VOIP protocols or sometimes known as stacks, their original proprietary SCCP, Multi Gateway Control Protocol or MGCP and SIP. MGCP, like SIP was supposed to be open and supposed to support any router or device; but since it shared a lot of it’s H323 roots; SIP was destined and pushed by the industry to be the standard for either phone, softphone, trunking, etc.  For all intensive purposes MGCP was so over by 2005.

So why is SIP so overrated for the original 7900 series?

  • Earlier models (like the original 79x0s) were limited; you could not have full duplex speaker, the speaker’s codecs was lame, ring tones sounded weird. no support for sidecars,
  • The line appearance keys on the original 79x0s had that silly rounded bubble.
  • Newer models did support full duplex, better speaker fidelity, but it was very picky on it’s settings XML file that would be pushed out by the TFTP server in the call controller system (or telephony server or PBX.) In the Java models (7970, 79x1s, 79x2s, and 79x5s) supported SIP more as an experiment and only on Cisco’s own SIP servers would they support. If you screwed up the XML file, the phone would literally stop reading it and disregard and giving you that “Unprovisioned” message
  • Those same newer models supported things like standard POE, Gigabit Ethernet, etc.

If you so choose to use 7900 SIP loads in your environment, the very first gen may only be better way. Why? Since older models are more capable of running off a Cisco SIP controller; because in it’s Settings user can literally edit IP or DNS addresses of the SIP PBX or service on the set itself, because it was possible to do so; not so much in later models that preferred to have configuration servers fed over TFTP. You could in the first generation, just have the phone hit the SIP controller, what I call the catchall IP or DNS address.

For those users who have say a UCx or that gawd awful 3CX or that Internet dependent FreePBX and you got a few sets you really need (under 20), I’d just recommend the next generation, the 6900, the 8900 and the SIP only 9900s as a better option along with the newer 7800 series, the 8800, and 6800 (that’s designed for the deprecated  Linksys/Cisco SPA customers.) In late 2020 the costs of the second generation x900s are relatively low in the greymarket.

Bragging about how you got a set that Cisco didn’t care for supporting at a time where SIP was still in the air; is so worthless. I’m not a fan of the screen phones because of it’s care and feeding. In short, the Cisco sets made after 2004 worked in theory and they settled beginning in the x800s.