Getting a Mitel 5235 IP phone to register with FreePBX

FreePBX / Asterisk 16.16.2 / all modules up to date

A few weeks ago I bought a BNIB (brand new in the box) Mitel 5235 IP phone, intending to get it to work as a SIP phone with my FreePBX 15 server, as I know others have done. The phone sat on the shelf until yesterday when I tried, unsuccessfully, to get it to download firmware from my TFTP server. I’m thinking that the firmware on the 5235 is very old, maybe too old.

Aside: Note that I have a Mitel 5330e, and have downloaded the firmware using TFTP, brought up the Web Configuration Tool using the IP phone’s IP address, and the 5330e has registered with FreePBX. So I’m relatively familiar with booting Mitel phones, and configuring DHCP options for Mitel IP phones on my pfSense firewall. Here is ta link to a description of the procedure I used:

Configuring Mitel 5330e on FreePBX 15

On the 5235, when I view version info, here is what I see:

Main Load Version: [Yes, all zeroes]
Boot Load Version:
L2Boot Load Version:

I’m wondering if anyone has any insight into how I might get the 5235 working, or where I can find firmware older than, say or earlier.

I’ve never done it, so YMMV, but it should be the same basic process as the 5330. The fact that the only firmware on the phone is the hardware load is troublesome, so I’d start with some Mitel fora first and see if they know anything about getting something loaded. My suspicion is that there’s a bootstrapper somewhere that can get the process started and (once you have that) you can start downloading software from either an HTTP or TFTP archive.

@cynjut Thanks for your reply. Yes, there was indeed a generous Good Samaritan from another community support site who provided SIP firmware for all the major Mitel versions (,,, and for the Mitel 5215, 5220, 5235, 5324, 5340, 5360, 5540, and 5560 IP phones. Many thanks for this contribution.

Since the Mitel 5235 I own was BNIB (brand new in box), I started by installing the first firmware version and proceeded through to Each version of the firmware allowed me to use the Web Configuration Tool (i.e, the IP address of the phone) to successfully register the 5235 as an extension on FreePBX, using a procedure very similar to what was described when I configured the Mitel 5330e. For reference the default password is admin/5235 .

A couple things to note about the Mitel 5235:

  1. The font on the display screen is quite tiny and I don’t think that it can be changed. This is probably why there is a stylus attached to the phone, which can come in handy for folks who can’t see small fonts without assistance. It is possible to use a fingernail in place of the stylus, but I can imagine how that might be a little problematic for those of us, like me, with poor aim.
  2. Although this isn’t true of the responsiveness of the phone itself, the response when accessing the phone through the Web Configuration Tool is surprisingly sluggish, altho’ it seems a little less so for the firmware.

For what it’s worth, I now possess SIP firmware for the 5235 and 5330e.

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