How do I get the phone mac address - Avaya 5610 IP Phone

That depends on whether you are using mac address filtering or not. You'll need to put the modem password into the phone once. If you are using Mac address filtering, then enter the phone's mac address onto the modem list first.

YES

The MAC address is the unique identifier for your network device. You can try to add the MAC address directly to your WiFi router in case someone turned this feature on you router.

To see your MAC go to "Settings - Wi Fi - Options Button - My MAC address".

A T-7316e not having an internet CAT5 connection does not have a MAC address.

To Display Bluetooth MAC address: *#2820#
To Display the WLAN MAC address: *#62209526#

Go to your management software inside the access point. Default IP address is 192.168.0.50. If you changed it, go to that address with a browser. Default login with "Admin" without a password. If you set up a different administrator id and password then login with those credentials.

Go to the "Advanced" tab. The setting on the MAC address settings are important here. Hopefully you know how to get the MAC address of the phone. I don' have the same phone so I can't tell you how to get it. Ensure that you have entered in the phone's MAC address and any other devices that you connect wirelessly to. If you have registered the MAC address under the second radio button or you have the first radio button clicked, you have a WEP or other password issue. Many public access point don't filter any MAC address and don't require passwords. When setting up at home, you do have to at least these up.

Hope this helps.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/mark_1e5d703456353ef9

This may be a problem with your router. Routers have a feature where you can control which computers can access the network using their physical address. This is called the Media Access Control (MAC) address. Every wireless card and network card in the world has their own unique address and is represented in hexadecimal format.
You'll need to notify your router of your phone's MAC address. On my netgear router, I access the router through a browser on a computer connected to it by typing www.routerlogin.net (i think... it varies with different routers) or the gateway ip address e.g. 192.168.1.1. Find the option for MAC address management, in my netgear it's called Access Control (i think) and there should also be an option to add MAC addresses. Add in your phone's mac address and try again.
Your phone's MAC address should be located on the box it came in or under the battery of the phone. The MAC address is in the format 00:A1:B2:C3:D4:E5:F6:7A.
Good luck

This may be a problem with your router. Routers have a feature where you can control which computers can access the network using their physical address. This is called the Media Access Control (MAC) address. Every wireless card and network card in the world has their own unique address and is represented in hexadecimal format.
You'll need to notify your router of your phone's MAC address. On my netgear router, I access the router through a browser on a computer connected to it by typing www.routerlogin.net (i think... it varies with different routers) or the gateway ip address e.g. 192.168.1.1. Find the option for MAC address management, in my netgear it's called Access Control (i think) and there should also be an option to add MAC addresses. Add in your phone's mac address and try again.
Your phone's MAC address should be located on the box it came in or under the battery of the phone. The MAC address is in the format 00:A1:B2:C3:D4:E5:F6:7A.

As for your messages undelivered, maybe you can try using the Nokia PC Suite to access the files and delete them via the computer. I'm guessing you might have a large number of these. The phone would begin to lose it's stability after about 200 messages (which is what i had in my inbox when it decided to refuse opening the messages).

If you are running C6E or later firmware, then the following keypad sequence is used to reset all provisioning paramaters to a "factory default":
[*][*][7][3][6][3][9][MAC][#][#]
Where MAC corresponds to the MAC address of the IP Phone which can be found on a label on the back of the IP Phone.
Since a MAC address can contain the letters A-F, then letters A/B/C can be entered via the [2] key on the dialpad, and letters D/E/F can be entered via the [3] key.
For example, an IP Phone with MAC address 00:19:E1:E2:17:12 would be reset to "factory default" when the sequence **73639001931321712## is entered on the keypad.

I just called Polycom and the guy said it starts with 0003 or 0004. Sure enough I had one of those numbers, it was the same as the serial number on the box the phone came in. This number is found on a sticker on the back side of the phone. Easy to find, but not labeled as a "mac address"