Comments on U-verse voice


One of the three services in a Triple Play package like U-verse is voice telephone service. U-verse is completely implemented over IP, so AT&T uses the standard VoIP (Voice over IP) protocols: SIP (Session Initiation Protocol), SDP (Session Description Protocol), and RTP (Real Time Protocol) with an analog terminal adapter integrated into the U-verse Residential Gateway (RG). 4-pin RJ-11 jacks on the rear of the RG provide analog phone service, which you generally connect to the existing telephone wiring in your house after you have isolated it from the drop coming to your house from the street. You can keep using your regular analog phones (but see discussion of Caller ID problems, below.)

U-verse uses a dry, digital-only loop

The loop from the street carries only the VDSL2 signal. VDSL2, like ordinary DSL, uses OFDM (Orthogonal Frequency Division Multiplexing) on frequencies above the audible range, leaving the baseband clear so the line can be shared with ordinary analog POTS (Plain Old Telephone Service). However, AT&T does not seem to use this feature; voice is available through U-verse only with VoIP.

The U-verse loop is also dry, there's no DC voltage as on a loop carrying conventional analog POTS or POTS combined with DSL. This has two implications:

  • You can't tell if the loop is active by connecting a phone to the network interface jack on the side of your house. You'll hear nothing at all, not even your own sidetone. Without special test equipment, you can only connect the Residential Gateway (or a compatible VDSL2 modem) and see if it synchronizes.
  • Copper loops sometimes become intermittent due to oxide buildups at the many splices and junctions along their paths. It's well established that a small DC sealing current can help break down those oxide buildups and keep the loop functional. Sealing currents need not be continuous; the DC current that flows when an analog phone is off hook usually suffices.

    On the other hand, U-verse loops are much shorter than most ordinary POTS loops so they probably contain fewer splices and connections. Maybe the problem won't be severe.

    U-verse voice is 64 kb/s μ-law PCM

    U-verse VoIP uses standard 64 kb/s μ-law PCM, the same digital format that telephone companies have used to carry voice for many years. This means your voice quality should be as good as analog POTS. Anything that works on a regular phone line (fax machine, modem, etc) should work fine on U-verse voice. In fact, the voice quality on U-verse is probably better than on POTS because the signal is analog only inside your house. The digital signal on the U-verse loop is much less suseptible to noise, crosstalk and hum than analog POTS. Like all digital communication systems, U-verse tends to work either perfectly or not at all.

    Some U-verse customers have reported lots of noise on their phones. This has never happened to me, and I suspect that when it does occur it's either a faulty RG or faulty or improper wiring.

    U-verse Voice Drawbacks

    Although our U-verse phone service has been clean and reliable (or as reliable as U-verse itself), it does have some drawbacks in comparison with competitive VoIP services.

    Power and Reliability

    Ordinary POTS phones are powered by the telephone company, so they'll keep working indefinitely during a power failure. With U-verse, you have to power the Residential Gateway on your end of the line. (It needs more power than could be sent down a phone line anyway.) The AT&T U-verse installer gives you a 12V DC power supply with a built-in battery to power the Residential Gateway for several hours during a power failure. After that, you're on your own.

    Also, if the RG fails, everything will be out - Internet access, TV and phone. You can't just connect a regular phone directly to the line from the street; it won't work.

    Like a lot of people, having mobile phones as a backup makes me much more willing to risk a wired phone service outage than in years past.


    Our U-verse phone service is $33/mo. This includes unlimited calling to the United States and Canada and many ancillary features (Caller ID, voice mail, etc) that cost extra with POTS. While cheaper than most POTS plans, this is still more expensive than many competitive VoIP service plans. For example, the VoIP bundled with my Speakeasy DSL service cost only $25/mo, and in addition to the same long list of features like Caller ID, voice mail, and unlimited calling to the United States and Canada, it also included unlimited calling to 30-some foreign countries.

    On the other hand, I never had much reason to call these other countries. Nor did I (or do I) make very many phone calls to the US anymore; email and text chatting became my primary forms of communication long ago. On the relatively rare occasion that I want to converse with voice (or video) I will usually use Skype or one of the instant messenger services (AOL Instant Messenger, Yahoo Messenger, Jabber, etc.)

    No support for user equipment

    Although U-verse voice uses the same standard VoIP protocols spoken by a very wide range of third party hardware and software products, AT&T buries the necessary SIP credentials (i.e., password) inside the Residential Gateway. You're forced to use its built-in analog terminal adapter. When I had Speakeasy DSL with their VoIP service, I called and asked for my SIP credentials and they gladly gave them to me.

    Several third party VoIP services support "BYOE" (bring your own equipment), and you can certainly access them through U-verse, i.e., by using U-verse only to access the Internet. But there are some drawbacks in doing so:

  • There's no guarantee that there will be enough capacity on the Internet path through AT&T's network to wherever your VoIP provider locates its IP-to-PSTN gateways.
  • The RG gives top priority to the traffic generated by its internal VoIP adapter. Nothing you do on your computer network can upset a voice call. But when you connect your own terminal adapter or phone to the RG, the RG treats it as just another computer, and it assigns the lowest priority to your computer traffic. Unless, as I do, you implement your own Quality-of-service (QoS) mechanisms on the flow of traffic from your LAN into the RG, your voice calls could be impaired if you simultaneously transmit or receive data close to the rated speed of your U-verse Internet access service.

    The nominal speed of the VDSL2 connection between the RG and the U-verse VRAD is 5 Mb/s up, 32 Mb/s down. (Some older and "problem" links still run at 3 Mb/s up, 25 Mb/s down, and possibly slower.) Even when your link runs at 5/32, the most that AT&T will even offer to sell you for Internet access is 3 Mb/s up, 24 Mb/s down. The built-in VoIP adapter is apparently not subject to these limits, while an external VoIP adapter would be. However, the data rate of a single voice call is less than 100 kb/s, and that's fairly small compared to these limits.

    Caller ID problems

    For reasons that are still not understood, the Caller-ID generator in the U-verse Residential Gateway is not compatible with some Caller ID displays. I had to insert a separate Caller ID display box in the line to our bedroom phone, which has a built-in caller ID display. That display works fine with POTS caller ID and with VoIP analog terminal adapters other than the one built into the U-verse RG.

    Slow Website

    The U-verse website is hard to navigate and slow compared to most other sites of its type. (It's still better than Verizon Wireless which definitely takes the prize for the most cluttered, flash-laden and hard-to-navigate corporate website.) Nearly every page is generated dynamically, which probably accounts for much of this slowness. Click on a link, and more often than not you'll see an animated pop-up saying "This may take a few moments, depending on your Internet connection speed". It's obvious when the page finally does appear that the speed of my Internet connection was not the determining factor, but the speed of the web server generating it.

    No Automatic Voicemail-to-email Forwarding

    This is probably the single biggest irritant I have with the U-verse voice service. When I was on Speakeasy, I could go to their website and ask that all of my voice mails be automatically forwarded to my regular email account, which was not provided by Speakeasy. But not AT&T! To listen to your voice mail online you must sign into AT&T's website, navigate to their "Message Center", and wade through all the AT&T "exciting special offers". As previously indicated, this can be quite slow and tedious. You can listen to each message by clicking a button on the webpage or you can manually forward it to an external mailbox, but you cannot have it done automatically. Even manual forwarding works on only one message at a time; you can't click on a group of messages and forward them all at once. Forwarding each message requires you to walk through a series of pages, entering your email address each and every time.
    Last modified: Wed Oct 6 21:14:14 PDT 2010