Calling UK mobiles from Mexico - San Crist!bal de las Casas

Assuming that you will have a decent WiFi connection one solution might be to use the Viber messaging app, which I find find suitable for such calls.

The paid-for 'Viber Out' function provides calls to any number worldwide at minimal cost, in a similar way to Skype, call quality is usually good and your mobile number that your Viber account is registered to is displayed to the called party.

Of course, if you are called back on that number you will incur the relevant roaming charges.

CardinalWolsey wrote: »

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Or, ease of adoption - Skype (which will also enable you to have an incoming UK number). https://www.skype.com/en/features/online-number/

Eh?
Did you mis-read the OP where he said
"I haven’t had much success using Skype to make these work calls in the past from abroad.".

There are all sorts of VoIP options for different needs.

If you will have a good internet connection then it's probably easiest for you to make the call directly using a phone app, software on your PC or a special VoIP phone. Viber, Skype and the various Betamax VoIP services (e.g. the ones listed on http://www.voip-comparison.com) all offer this option, amongst many others.

If your internet connection isn't so good there are services where you either dial a local number which connects you to the recipient (e.g. LocalPhone.com) or where you set up a call-back which first calls you, then calls the recipient (e.g. the Betamax VoIP services). In these cases you are using the local phone network with VoIP being used for the international part. You would need a local phone number for this, but I'm sure you would be getting a Mexican SIM card anyway.