Analog PSTN options for a novice?

I have recently moved our office over to almost a 100% sip environment.

What we have realized is we still want an ANALOG backup line for two reasons

  1. If our internet is down or call quality is really poor due to issues out of our control, we can then use the analog.

  2. In the event of a power outage We can quickly move the analog line to a analog phone.

We do very little volume, but this is what I am trying to figure out.

  1. Should I go with an analog card and just setup a ZAP/dahdi trunk
  2. Should I go with a sip ata or gateway and use that?

Prices are pretty similiar…

Any suggestions?

Last, we currently have a fax line, is it a no brainer to never run an analog fax through the pbx? The reason I ask is I was thinking we could save some money if I used the Analog fax line through the pbx, but in those extremely rare scenarios something is down like the internet, I could utilize the fax line for outgoing & incoming calls and just temporary disable the fax.

I’m sure a lot of these questions to a VOIP PRO indicate I don’t know what I am talking about, but there is good reason, I don’t:), please lend your opinions on a good practice of how I should implement PSTN lines for a small office.

Please assist, I would really appreciate anyone’s insight!

Cards work really fine, but one gateway has some advantages for me:

You dont need to open the your Server for the Installation.

Dont use CPU resource for work.

Extra features base on the gateway software.

Fast installation and easy to replace between PBX