The good news is that unlike alarm systems, you don't have to worry about any special wiring considerations with these units (no RJ31X jack to worry about). The so-so news is, these units may or may not work with your VoIP service. Many users report that they work just fine, or can be made to work with a little effort.

If things aren't going well, one trick that is sometimes used to improve connections is to take an inline DSL filter (the filter that is used by DSL subscribers to filter data noise out of normal telephone conversations, similar to the unit shown at the left) and connect it backwards to the device in question, that is, inserting the plug of the filter into the device rather than the wall jack (this has also been known to improve performance with certain FAX machines, although some VoIP providers offer specific support for FAXing so this is less likely to be an issue). Another thing that some have suggested is that call waiting should be disabled, although that probably won't make a big difference unless people often try to call you while your electronic devices are "phoning home."

Another thing you should do is check the menus to see if there is any way to adjust the data transmission speed. Generally, the slowest setting possible will give the best results. ReplayTV users should set the connection speed down to 19.2kbps. With a stand-alone TiVo or an early model DirecTiVo (but not a Series 2, apparently), changing the dial prefix to ,#034 changes the internal modem speed to 28.8kbps, and ,#019 changes the internal modem speed to 19.2kbps (include the leading comma in both cases). With a Series 2 TiVo, the following codes may work instead: ,#338 to connect at 38.4kbps, and ,#396 to connect at 9.6kbps (we recommend the latter, and once again, the leading comma must be included). Some have reported successful connections by using an external modem (similar information here) and setting the connection speed of the modem to 19.2 or 9.6 or even 2.4kbps (here is a thread on using DirecTiVo with VoIP). There is also a firm that sells external modems for the TiVo.

Another possibility is that there may be VoIP adapter-specific service codes you can prepend to what your home electronics unit dials, which can be added in addition to one of the above dial prefixes, or as a standalone code. If added to one of the above dial prefixes, these service codes should be placed AFTER the above prefix, but BEFORE the telephone number (if you have to enter the number manually), and may need to be followed by a comma. Some VoIP adapters require a short pause after dialing any "service code", before they will accept the telephone number, and if that's the case you'll have to use a comma (or whatever causes the device doing the dialing to insert a pause) after the code. For the sake of simplicity we will show codes in the following examples with commas appended, but bear in mind that you may not need them or that your home electronics unit may use a different "pause character" in its dial prefix codes.

As an example of a VoIP adapter-specific service code, the Linksys/Sipura family of adapters will recognize the use of the service codes *027110, or *027111, to force the use of the G711u or G711a codec, respectively, regardless of your current bandwidth saver selection. However, this may not work with all VoIP providers, and in any case should not be needed if you do not have "bandwidth saver" enabled. If you select a codec your VoIP provider doesn't support, you'll get a fast busy after dialing the complete number. As another example, with a Cisco ATA-186 adapter or a Linksys PAP-2 adapter, it has been reported that *99, will force the adapter to use a better codec for FAX and data (with the Linksys PAP-2, this code is configurable by your VoIP provider, so it may not work as expected with all providers. Also, if when you dial *99, there is a delay before you hear the second dial tone, you or your provider may need to insert a rule in the PAP-2 dial plan to provide dial tone immediately after the *99 is dialed - for example, *99S0| or *xxS0| at the beginning of the PAP-2 dial plan).

So, for example, with a stand-alone TiVo and a PAP-2 or an ATA-186 VoIP adapter, you could try using ,#019*99, as the dial prefix, or simply ,#019 or just *99, (you could even try all three and see which works best). Note that in the first example, only the "*99" part of the string (followed by a pause and then the phone number) is actually dialed — the ",#019" is used internally by the TiVo unit itself to set the connection speed, and is not dialed out to the VoIP adapter. We do not know the applicable service codes for VoIP adapters other than the Cisco ATA-186 and the Linksys/Sipura family — if you do, please send them to us. (By the way, not to make things more complicated, but in theory you could also add the *70, "cancel call waiting" service code to prevent incoming calls from interfering with your connection, so once you get the system connecting reliably, try adding *70, to the end of the dial prefix — if it still works, it should prevent incoming calls from knocking your unit offline.)

One TiVo user wrote in his blog that, using a RCA DVR39 DirecTiVo unit, he was able to make it work using the following settings:

Dial Prefix: 12122773895
Call Waiting Prefix: *99,,*70,,#019,,     (Use *99 only with a Cisco ATA-186 adapter - see below)
Phone Available: Off
Dial Tone Detect: Off

In the above settings, the "12122773895" is a TiVo local number in New York City that apparently seems to work when others will not. In the "Call Waiting Prefix", *99 is a code specific to the Cisco ATA-186 adapter that forces it to use a better codec, but as mentioned above, if you have a Linksys/Sipura adapter you may need to substitute *027110 or *027111 (actually we suspect that the writer of this blog entry should have done that, because he says that he is using a Linksys WRT54GP2 adapter, and Linksys adapters are based on Sipura technology). *70 is the "cancel call waiting" code, and ,#019 changes the internal modem speed to 19.2kbps, also as explained above.

Since many VoIP companies default to using the G711u codec, we suggest that those with Linksys/Sipura adapters first try just *70,,#019,, for the "Call Waiting Prefix", and if that doesn't work, try either *99,,*70,,#019,, or *027110,,*70,,#019,, (you may or may not need the final two commas in the string - each comma adds a short delay before the next sequence is dialed).

Here's another approach to take — sometimes, if you contact your VoIP provider's customer service, there are settings they can change on their end that will improve performance (two changes that have been suggested are to set the packetization rate to 10ms, and to disable silence suppression, however, these may not be applicable to all providers or all VoIP adapters). This is usually not something you can do on your own, and your VoIP provider's customer service department may or may not have a way to fix the problem. If nothing else seems to be working, try temporarily disconnecting all other phones and phone devices on the line. Sometimes another device on the line will change the electrical characteristics of the line enough to interfere with data communications (this is true even when traditional wireline phone service is in use).

In some cases, there may be a much better solution than messing with dialing codes and configuration settings — for example, with some TiVo units it's possible to directly connect them to your broadband connection, bypassing your VoIP service entirely. Some TiVo DVR units can be directly connected to a wired or wireless network. It is said that other types of TiVo units can be modified to use a local network connection, but that requires a higher level of hardware and software expertise that is beyond the scope of this discussion. You can read more about that at several web sites, including this very detailed set of instructions on how to get your TiVo on the network (and how to add a web Interface to your TiVo, and some other interesting information) but this requires the purchase and installation of an Ethernet Adapter Card). Additional sites with "various HOWTOs for those of you using Ethernet with version 3.0 of the TiVo software" are in this TiVo forum post. Here are a couple more message threads on the use of TiVo and DirecTivo with VoIP, also here is a thread that includes a schematic diagram of the TiVo Serial Cable.

And remember, Google is your friend — try doing a search using the name of the service you're trying to make work, plus the name of your VoIP provider, and see what pops up. If you get too many hits, add phrases like "connection problem" or "can't connect" to the search (be creative!) and see if that narrows it down any. Almost certainly many people have experienced the same problems, and some of them have solved the problem and posted how they did it!

Please note that many people don't have to do any of what we have written in this section — they simply connect their home electronics devices up in the normal manner to their inside telephone wiring, and when that is switched over to VoIP, everything still works. We don't know why it's that way for some people but not for others!