I've used two OBi & GVoice for a small business for 3 years with no problems.
There is a massive problem starting from Friday. Incoming calls just aren't working.
Our phone system isn't super critical to business, so I am going to wait and see for a week.
Honestly the OBi 200s have worked well for years. Silent workhorses, with no problems.
We use some basic QOS at the router / switch, and set up MAC filters for each device. Has worked well for us.
We were paying $40/line for copper lines. 36 months * 2 Obis * $40/month = $2,880 for two years of lines. Use all of our old analog stuff.
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25 users sounds like a bigger organization. I would probably buy a commercial service.
If this isn't fixed by Friday, I'm going to port over to a pay service. Alas, the good times are over.