We have a M2727 Laserjet Printer/Fax . We can print, and we can receive fax, but our problem is sending a FAX.. Keeps giving us an error code of 49. Please advise Thank-You, Marla

Error 49 is typically an issue with corrupted firmware on your device. Firmware is software that tells the actual hardware how to process things like prints and faxes.
Updating your firmware is pretty simple. First you need to download the firmware utility from HP for your printer. For your model, here it is:
http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&prodTypeId=18972&prodSeriesId=3377075&swItem=ma-55531-7&prodNameId=3377076&swEnvOID=228&swLang=8&taskId=135&mode=3
Then, follow the directions from HP to update the firmware:
Process:

1. Download the flash firmware updater file from HP.com to the PC desktop.
2. Turn the printer off and then back on to clear main printer memory.
3. Double click on the M1522_MFP_Series_FW_Update-20100902.exe. An HP firmware update window will open.
4. Select the appropriate MFP in the dialog window. If you assigned a different name to the HP MFP, choose the name that represents the correct printer.
5. Click on "Send Firmware" when ready to proceed.
6. The progress bar will begin to move to the right indicating information being transferred.
7. DO NOT power cycle the product or the PC during this process or the product may become unstable and or unusable without further attention from HP. The flash firmware update can take up to 5 minutes to complete. Please be patient.
8. During the product flash firmware update, the display on the product control panel will display "Erasing - Programming - Complete - Hewlett-Packard - Ready - Initializing - Ready". Once the download is finished the printer will be in the Ready state.
9. At the conclusion of the firmware update, the dialog window will show a smiley face. Click on exit.
10. The flash firmware update process is complete.
11. If it is desired to verify the update, use the control panel reports menu under setup to print a configuration report. The configuration report will show the current firmware revision in the Product information block, Firmware Datecode: 20100902.

I found this on the HP website:

HP LaserJet M2727 Multifunction Printer Series - 49 Error Message Is Displayed While Faxing ISSUE: The printer control panel will be displaying 49 service error while sending faxes. The receiving fax will be lost, and the printer will display the same error even after reboot. SOLUTION: Performing a factory reset and a firmware upgrade is the only solution for this issue. Step 1: Performing a factory reset Restoring the factory-set defaults returns all of the settings to the factory defaults, and it also clears the fax header name and phone number. CAUTION: This procedure clears fax numbers and names that are associated with one-touch keys and speed-dial codes, and deletes any pages that are stored in the memory. The procedure then automatically restarts the product. Perform the following steps to restore the factory-set defaults: 1. On the product control panel, press Setup . 2. Use the arrow buttons to select Service , and then press OK . 3. Use the arrow buttons to select Restore defaults , and then press OK . The product automatically restarts. Step 2: Firmware upgrade After coming to ready, upgrade the printer firmware from the HP website. The issue can be fixed with any of the firmware upgrade available now. Firmware version 20080505 and higher versions have the fix. You can download firmware version 20080612 from the HP LaserJet M2727 Firmware Update 20080612 webpage. Click here to go to the HP LaserJet M2727 Firmware Update 20080612 webpage (http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&prodTypeId=18972&prodSeriesId=3377075&swItem=ma-55531-3&prodNameId=3377076&swEnvOID=228&swLang=8&taskId=135&mode=4&idx=3) . The preceding steps will resolve the issue.