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Gigaset SIP/DECT Handsets For 2010: Part 6 – SL78H

Introduced in early 2009, the Gigaset SL78H is the top-of-the-line cordless handset that they offer in North America.

Like the C59H and S79H, the SL78H is only being offered as an expansion handset with respect to the IP-capable A580IP and S675IP systems. You may see it offered as part of the SL780 or SL785, but these are not IP-capable systems.

As I’ve moved up the product range there has been a natural progression in features and physical attributes. Each better model builds logically upon the previous, but adds certain improvements in hardware or software.

At the top of the range the SL78H is physically a very different device. To start, it’s heavy. Unlike the prior models there is a lot of metal in the SL78H. Even the keypad itself has a brushed-metallic finish.

The handset’s frame is chrome-plated metal. The charging base is also chrome-plated metal, and heavy enough to be small yet hold the handset securely, without fear of it falling over.

All this use of metal gives the SL78H a very gratifying feeling in the hand. It simply feels like a high quality device. However, with an asking price of $150 such build quality costs.

The display on the SL78H, at 2.2 inches is larger than those on lesser models. It’s a TFT LCD resolving 240 x 320 pixels at 18 bit color depth (aka 256k colors.) It’s big, bright and sharp.

The entire back of the SL78H is a removable plastic cover. With the belt clip and the back removed you gain access to a mini-USB port and the battery pack. Like the lesser models, you’ll also find the driver for the speakerphone under the back cover.

Unlike prior models, the SL78H does not use standard AAA sized batteries. Gigaset has instead used a custom Li-Ion battery pack that’s said to deliver 200 hours of standby time or 15 hours of talk time.

The mini-USB port allows the use of the Gigaset QuickSync software for Windows as previously described. Like the S79H, the SL78H allows up to 500 contacts in memory, synced to outlook.

Of course, you can upload caller ID images, which can take advantage of the larger, higher-resolution LCD display. In fact, the display is so nice that I thought you might appreciate a gallery of menus shots to illustrate this fact.

If you click on the large image below it will invoke an image gallery. There are 17 images, each is reasonably close to a 1:1 pixel relationship with the display of the phone. I’ve done only minimal resizing, cropping and gamma correction so these images should be a fairly accurate representation of what we see on the SL78H handset.


It’s very clear that as cordless phones go the SL78H has a spectacular display. It’s easily the best of the Gigaset range at leveraging the various data display capabilities (news, email, sms) of the handset.

While the menus are very clear and easy to navigate I found that the improved display recast the screen saver feature in an entirely new light. When parked in the charging stand the handset acted like a small digital photo frame showing a family picture. While relatively trivial this was nonetheless a nice feature for home use.

In many ways the feature set of the SL78H is a mirror of the S79H, but in a different physical form. Where they differ is with respect to headsets. The SL78H supports the use of a Bluetooth cordless headset….and only a cordless headset. Its metal frame is continuous, lacking the connection for a wired headset.

I tried using the SL78H with two models of Plantronics headsets; the CS510 and Savi Go. Both were easily paired to the SL78H and worked well.

Sadly, the Bluetooth radio on the SL78H did not permit the use of wideband audio in the case of the Savi Go. Even though the Gigaset was on a G.722 encoded call, the audio at the headset was narrowband. Since wideband capable Bluetooth headsets are a comparatively rare this was not entirely unexpected.

I am hoping to acquire a Bluetooth wireless speakerphone and try it with the SL78H. I feel that even though the pair would not be wideband capable they might be a better solution that the handsets built-in speakerphone capability.

The Bluetooth radio can also be used as a data link to your PC. When setup in this fashion it replaces the USB connection for conveniently syncing contacts, uploading pictures and ring-tones.

Our use of the SL78H has been limited to the home office, for when I put one on our home phone line my wife complained about the keypad. She didn’t like the fact that the keypad is a single, smooth surface. She felt that, like the snom m3 handsets a couple of years ago, the smooth keypad made dialing more difficult since she couldn’t feel the transitions between the keys. She felt it caused her to miss-dial a lot so she prefers the S79H handset.

My feeling is that the SL78H is a great flagship for the Gigaset DECT range. It’s very well built and has a tremendous feature set. It’s the ultimate cordless phone for a large and very tastefully decorated house. It should be featured in fashion & décor magazines because it truly is house-techno-bling.

While that may appeal to some, it’s just a little over-the-top with respect to our humble dwelling. Given the choice between various models we’d rather have more of the S79H handsets. They may not be all chrome and sparkle, but I think that they’re the better value.

In an unrelated note: has anyone noticed that the various Gigaset handsets follow the same naming conventions as Mercedes cars? I’m told that the A , C, S & SL class designations were used with permission from Mercedes. Apparently there is some solidarity amongst German manufacturers.

This Post Has 29 Comments
    1. No. None of the Gigasets can handle alpha numeric entry, so no SIP URIs. In my case I can work around this using the My.OnSIP user portal, which allows calling by SIP URI by performing call setup like a callback service.

  1. Thanks for the review. I was wondering if you know of any SIP/DECT Handsets that support SIP TLS/ SRTP. I would prefer to have the option to secure my media.

    1. For the moment I’ve not been able to positively confirm TLS/SRTP capability in any SIP/DECT systems. I suspect that this would be possible in the realm of the commercial Polycom KIRK or Aastra systems. Not some much in the consumer/SMB oriented snom & Gigasets.

        1. Be aware that a US version of the M9 has yet to be released. The initial release operates on Euro frequencies and are not legal for use in North America.

          Also, bear in mind that you can also wrap your voip traffic in a VPN. This is most typicalyl useful when you have control of both ends. For example, trunking between two locations. Not so much when terminating to a service provider. But then again, most service providers don’t support TLS/SRTP either.

  2. Hi,

    Great reviews of the Gigaset line-up.
    I live in NYC and the 2 phones I’m considering are the S675IP and the SL785.
    They are about $40 off on price which is not an issue. What I don’t understand is the price difference between the SL78H ($150) and the S79H ($70).

    Do you have any thoughts on the S675IP vs the SL785?

    If I get the SL785, could I have the S79H as my 2nd handset using the SL785 base?


    1. The big difference between the SL785 and S675IP is that the later is SIP-capable. It can register with VoIP services directly. The DECT base for the SL785 cannot. It has only the analog line interface.

      Once you have a basic system and start adding extra handsets you can go in any of 5(!) directions. The SL78H is the top of the line, with Bluetooth and a nice big color display. But for my money the S79H is a better choice since I like using a wired headset around the house.

  3. Thanks. A couple more (newbie) questions.

    It looks like the S675IP is “better” since it’s SIP capable (barring the super nice handset of the SL785). I’m not using a SIP service yet, but it’s nice to have the option (I currently have Vonage with I don’t think would be compatible).

    Would the best of all worlds be to get the S675IP (for the SIP base) with the SL78H (for the Bluetooth headset)?

    So I’m thinking of going with the S675IP and getting the S79H as the expansion headset.
    If I eventually register with a SIP service, will I be able o make SIP calls with the S79H?

    So from what I understand, the base of the SL785 has nothing to do with the Bluetooth. The Bluetooth is all in the headset?

    Thanks again. This is very helpful.

    1. Q: It looks like the S675IP is “better” since it’s SIP capable (barring the super nice handset of the SL785). I’m not using a SIP service yet, but it’s nice to have the option (I currently have Vonage with I don’t think would be compatible).

      A: “better” is a matter of opinion or application context, but yes the S675IP is more flexible. You could plug it into your Vonage box using the analog line jack.

      Q: Would the best of all worlds be to get the S675IP (for the SIP base) with the SL78H (for the Bluetooth headset)?

      A: Possibly, if the cordless headset is important to you. I should not that the Bluetooth radio is not capable of G.722 / HDVoice calls. Not to seem snarky, but since you’re using Vonage now you’ve yet to experience HDVoice, so you won’t miss it.

      Q: So I’m thinking of going with the S675IP and getting the S79H as the expansion headset. If I eventually register with a SIP service, will I be able to make SIP calls with the S79H?

      A: Yes, any models Gigaset handset can make SIP calls via the S675IP base.

      Q: So from what I understand, the base of the SL785 has nothing to do with the Bluetooth. The Bluetooth is all in the headset?

      A: That is correct.

  4. If I get the S675IP with the S79H as the extra handset, does the answering system reside in the base of the S675IP? If not, how does it work?
    I plan on hiding the base in a closet with my cable modem and my wireless router. Does the base serve any purpose? Will I be able to listen to the a message as someone is leaving it from the handsets? Do both handsets have a message waiting indicator?
    Finally do the handsets have talking caller ID?


    1. Q: does the answering system reside in the base of the S675IP?

      A: Yes.

      Q: Will I be able to listen to the a message as someone is leaving it from the handsets?

      A: I’m not sure. We don’t, but it may be possible. You could check the user manual as these are available online.

      Q: Do both handsets have a message waiting indicator?

      A: Yes.

      Q: Finally do the handsets have talking caller ID?

      A: Not as far as I know.

  5. Great review of the whole Gigaset series. Definitely the best on the web that I could find. It inspired me to get the S675IP and I couldn’t be happier. Thinking about adding a second line with the S79H handset. Thanks for all the hard work!

  6. Another thanks to you…

    I was debating getting one of these, and when my regular landline cordless broke, I took the plunge for $130 shipped from Amazon.

    Awesome setup, VoIP capability is excellent! Currently, I use a device on the analog port (bought it when it was a tk6000 for $100 for free lifetime service) and then 1 VoIP connection to a friend’s company, 2nd VoIP to my internal Asterisk (Elastix) server.

    Having the device, and the friends company, I was able to rid myself of an $85/mo AT&T bill, after porting the number.

    The ability to select a line on-the-fly with the #1 – #6 on the end of the dialed number gives infinite dialing flexibility.

    Thanks for the excellent reviews – MUCH appreciated!

  7. Great series of articles. These have been very useful in my search for an extra handset for my S785IP system.

    Your review of the SL78H handset states that the SL78H does not have a 2.5mm jack for wired headsets. This is a little confusing since the Gigaset website lists that the SL78H supports “Headset connection | corded 2,5 mm | Bluetooth®”.

    Do you have any idea whether this is a minor update since your review?

    1. I don’t believe so. A quick look at the SL78H user manual offered online reveals no reference to a wired connection. Not in an illustrations or the copy. I think that the web site is simply in error.

      Given the metal frame it would be troublesome (ie costly) to add the jack to the SL78H.

  8. Great website and a great resource. I actually purchased a 675IP with the S67H handset and it has worked very well. That being said, I coveted the nice hefty feeling of the SL78H and managed to get a S785 Duo (2 SL78H handsets) for a very decent price.

    Upon setting them up and registering them against my existing S675IP base station I am unable to get them to dial out on their SIP connection. They only will attempt the fixed line. Have you had any experience with this or do you have any insight? I can receive inbound calls by VOIP on them no problem. But dialing out they will not attempt to make the call over VOIP.

    Thanks for any help!


    1. Dan,

      If you log into the web GUI for the base you should find a menu called “number assignment”where the dialing preferences are established for each handset. You choose which line each handset will use as a default for outbound calling. You can also control which accounts ring on each handset in this same menu.

      1. I hav the exact same problem. To do outbound IP calls with the handset, I first have to press an “IP” button which sits in the bottom of the display. If I just punch numbers and press the green button, it uses the fixed line.

        The “Number assignment” section does nothing to solve the problem :-(. It is a really nice handset…

        P.S.: I’m using a s675ip base. The other handset doesn’t have this problem.

        1. I have the same problem too. SL78H handset, S675 IP base. The default line selection on the base has no effect. The SL78H always tries to used the fixed line and fails. It only works if I push the IP button first. This is a problem for everyone else in the house. Did you ever find a solution?

          1. I discovered that pressing the “Send” button longer when finished entering the numbers would send the call to the IP line. It doesn’t work with some function such as Redial.

            It’s funny because I recently bought 4 C610H handsets and they don’t have this problem. I’m sure it would be something easy to fix in the firmware.

  9. Michael,

    Great resource and website. I live in Switzerland but speak English. We bought the S675IP base station and a couple of Gigaset handsets (the SL78H and the one which came with the S675IP station). We use the SL78H as our main phone.

    I have two questions about this one that you may be able to help with. The answering machine speaks to us in German (date and time a message was received, how many messages etc.). I wrote Siemens asking how to change this to English and they gave me a series of key presses. Unfortunately they did not tell me from where in the menus I should execute those key presses and did not respond to my request for further detail.

    Secondly, when a call comes in and is taken upstairs on the handset that came with the base station, we can’t figure out how someone downstairs can join in on the call. At the moment picking up the phone upstairs takes the call but if it is for someone downstairs next to the SL78H, that person has no way of connecting to the caller that we can figure out. The display of the SL78H says “Fixed line in use”. If we hit the green button to answer a call it simply takes us into our redial list of the last set of calls we have made with that handset. I have a feeling what we need to do is to use the SL78H to make an internal call to the handset on which the call has been answered upstairs. Is that going in the right direction?

    Anyway, thanks if you have some thoughts to steer me straight on these two points. I really love the handset and think we will pick up a second.


    Dave M

  10. Is it me or does it seem like the 17 image gallery doesn’t work? I click on the image and only one picture appears of a couple wtih a dog on some stairs.

    1. Yes, over the evolution of the site I’ve used some WordPress plug-in, but then found them troublesome and so had to remove them. That gallery plug-in was something that became problematic so it’s gone now.

  11. how up to date is the review of the SL78H with the new 2012 firmware releases of this model? Is this review going to be updated to reflect the new features brought to the handset such as being able to dial SIP URI now?

  12. Does anyone know if the DECT 6 or EURO DECT is implemented in the base or handset or both ie can i use a euro DECT handset with the Nort american DDECT 6 base?

    1. The radio in each device must be tuned to the correct band. That means that gear made for us in North America will not interop with gear made for use in Europe. At least this is the case with the Gigaset hardware that I have used. I actually imported a system from the UK before they were offered in the US.

      Someone might make DECT gear that’s flexible enough to switch bands, but I expect that would be in the higher $ enterprise DECT gear from the like of Aastra or Kirk.

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