I have recently upgraded my mobile phone to a Nokia E51, partly because I wanted to test out it’s potential as a SIP extension on our Asterisk network. This, of course, opens up the possibility of having one phone that you use whether you are in the office, on the road, or even at home. The detail of these scenarios needs to be determined by your particular circumstances, but it is certainly feasible.
There is plenty of information on how to actually set up this phone on an Asterisk system (Google is your friend here), so I will merely say that this aspect of the test was pretty painless. Within minutes of taking the E51 out of it’s box I had it registered as an extension and happily making and receiving calls. Personally I would rather not have this as my only office phone, so any incoming calls are actually routed to both my desk phone and my E51, but you may wish to set it up differently.
Whilst the E51 has great battery life in what might be described as a traditional setup (i.e. not using the wi-fi capability) it is a known fact that wi-fi does drain the battery much more quickly than would otherwise be the case. This phone is very much business-oriented, so is designed to have pretty good battery life (amazing when you have it in your hand and feel how slim it is). I have heard estimates of 4 or 5 days between charges mentioned. All that goes out of the window when you turn wi-fi on. I have been doing a lot of testing over the last few days, so my use is atypical, but I have still had to charge the phone once a day ! I would expect that to improve slightly when my testing is complete, but I can’t imagine it lasting more than 2 days.
Anyway, back to the Asterisk interoperability. The E51 allows you to choose which type of call routing (i.e. mobile or internet) to use as default. If you choose internet, it will always fall back on standard mobile calling should the internet route fail. In practice this seems to work well, with one exception.
Having one device for all situations means having a single telephone address book. At first glance this might seem to be ‘a good thing’ and in truth it is…but it did throw up one interesting problem. As I travel abroad from time to time I like to store phone numbers in my mobile in ‘international’ forma, namely with a plus sign at the start, followed by the 2-digit country code, followed by the actual number. So, for instance, I would store our office number as +441233888240
This is all well and dandy, except the first time I fed such a number into an internet call, and therefore on to Asterisk, it didn’t work. It didn’t work to the extent that the call was not made rather than passing through from Asterisk to the mobile network. Thinking the problem was in Asterisk, I looked in the log and found….nothing ! A bit more testing suggested the phone was trying to place the call via Asterisk, but it wasn’t getting anywhere.
To cut a long story short, it transpires that passing a plus sign to Asterisk, without specific consideration for that within an outbound route, will result in the call being dropped pretty unceremoniously. So I proceeded to add the following to the outbound route dial pattern ‘+|.’ This matches the plus sign, strips it out and then passes the rest of the string on to the relevant trunk. This is important as stripping more out would remove the country code, and you’d get into a bit of a tizz trying to put it back on.
The IAX2 trunk I use for most outbound calls expects national numbers without country codes or international numbers starting with a ‘0′ followed by the country code. Since I wasn’t passing numbers in either of these formats, and didn’t want to reconstruct my dialing logic completely, I set up a second trunk in asterisk for the same provider. I haven’t tested this with a SIP provider, and I have my suspicions that it wouldn’t work, but for IAX2 it is fine. Within the second trunk I know what’s coming in (i.e. an international number starting with the 2-digit country code) so I merely tag ‘00′ on to the start (using ‘00+Z.’) and send it off down the trunk. So far it works very smoothly and I can have all my mobile phonebook numbers in international format.
